Garage renovation with structural shenanigans
Discussion
Hi everyone,
Without being rude, this is one of those posts where I’m looking for answers from proper experts or people with relevant experience. As much as I normally love folks with ‘helpful suggestions’ I’ve got armfuls of that already on this particular project
I’m embarking on a garage renovation that includes some relatively major structural work to the house - I ‘think’ I’ve got the right expertise involved but I’d love a little sense-check from some forum members - massive thanks in advance.
Background
My house is a fairly typical four-bed detached house on a housing estate built in the early 90s. The house has a double garage on the left which is ‘tucked in’ under the first floor. That means that the left of the double just has a basic pitched roof above it, but the right of the double has the first floor of the house above most of it.
That means that the garage has two piers.. one between the two garage doors and one right in the middle of the floor space that holds up the corner of the first floor. Hopefully that makes sense.
What’s the problem
Well, the huge pier in the middle that holds up the first floor means that any ‘proper’ car that goes into either side of the garage… you can’t get the door open. It’s almost like two single garages, which is really sod-all use.
What’s the plan..
Together with a structural engineer, we’ve a plan to remove both piers. The essentially decorative one between the garage doors, and the structural one that holds up the first floor (by supporting two RSJs). There’ll be a big RSJ that runs down the middle of the garage from the back to the front. That’ll sit on a big pier at the back, and then a large RSJ that will run across the top of the new single garage door and sit on top of two vertical steels to crate a ‘goalpost’ inside the garage door aperture, that’ll go down own two new 1m2 pads either side of the door. Bingo, I end up with one massive double garage with a big single door and no pillar in the middle - so much room for activities!
So what’s my ask..
I’ve had the structural engineer design the work
I’ve had a couple of quotes and in doing so found a company that specialise in installing structural steels within domestic buildings, they seems fantastic, have great reviews, give me a real feeling of confidence, will do all the work and deal with building control too
I’ve confirmed with everyone I’ve asked that there’s no planning permission required here because from the outside, literally the only difference will be that two doors become one, it’s be a miracle if anyone but me even notices the difference.
I’m going to inform my insurance company and ensure coverage during the works.
I’ve got two garage door companies who’ll come once the work’s done, measure up and quote/supply a new door (while I wait for that there will just be a huge plywood cover that fills the hole). I have a back garage door and an internal garage door so will still have access.
I’ve a plan to buy a temporary ‘storage tent’ so I can get everything out of the garage and into the back garden so that it’s safe, dry but fully out of the way. The back garden is secure and anything particularly valuable will go into the house instead.
I’ll be making sure that all companies involved have their own insurances too.
I’ve asked about necessary fire-proofing and water/rust proofing but I also assume that’ll be covered off by the building regs.
So then.. what have I forgotten? Is there someone I’ve missed? What should I be looking out for? Or asking for? What pitfall am I about to step into? If you were doing this project, what would be your biggest concern?
Hope that all made sense and all expert replies gratefully received. I’m really keen to do this work (as you can imagine - going from two s
t spaces to one massive one is such a petrolhead opportunity) but if I accidentally collapse my house or do something stupid that’ll cost a fortune to resolve - I’ll kick myself (and the Mrs will join in!)
Thank you!
Without being rude, this is one of those posts where I’m looking for answers from proper experts or people with relevant experience. As much as I normally love folks with ‘helpful suggestions’ I’ve got armfuls of that already on this particular project
I’m embarking on a garage renovation that includes some relatively major structural work to the house - I ‘think’ I’ve got the right expertise involved but I’d love a little sense-check from some forum members - massive thanks in advance.
Background
My house is a fairly typical four-bed detached house on a housing estate built in the early 90s. The house has a double garage on the left which is ‘tucked in’ under the first floor. That means that the left of the double just has a basic pitched roof above it, but the right of the double has the first floor of the house above most of it.
That means that the garage has two piers.. one between the two garage doors and one right in the middle of the floor space that holds up the corner of the first floor. Hopefully that makes sense.
What’s the problem
Well, the huge pier in the middle that holds up the first floor means that any ‘proper’ car that goes into either side of the garage… you can’t get the door open. It’s almost like two single garages, which is really sod-all use.
What’s the plan..
Together with a structural engineer, we’ve a plan to remove both piers. The essentially decorative one between the garage doors, and the structural one that holds up the first floor (by supporting two RSJs). There’ll be a big RSJ that runs down the middle of the garage from the back to the front. That’ll sit on a big pier at the back, and then a large RSJ that will run across the top of the new single garage door and sit on top of two vertical steels to crate a ‘goalpost’ inside the garage door aperture, that’ll go down own two new 1m2 pads either side of the door. Bingo, I end up with one massive double garage with a big single door and no pillar in the middle - so much room for activities!
So what’s my ask..
I’ve had the structural engineer design the work
I’ve had a couple of quotes and in doing so found a company that specialise in installing structural steels within domestic buildings, they seems fantastic, have great reviews, give me a real feeling of confidence, will do all the work and deal with building control too
I’ve confirmed with everyone I’ve asked that there’s no planning permission required here because from the outside, literally the only difference will be that two doors become one, it’s be a miracle if anyone but me even notices the difference.
I’m going to inform my insurance company and ensure coverage during the works.
I’ve got two garage door companies who’ll come once the work’s done, measure up and quote/supply a new door (while I wait for that there will just be a huge plywood cover that fills the hole). I have a back garage door and an internal garage door so will still have access.
I’ve a plan to buy a temporary ‘storage tent’ so I can get everything out of the garage and into the back garden so that it’s safe, dry but fully out of the way. The back garden is secure and anything particularly valuable will go into the house instead.
I’ll be making sure that all companies involved have their own insurances too.
I’ve asked about necessary fire-proofing and water/rust proofing but I also assume that’ll be covered off by the building regs.
So then.. what have I forgotten? Is there someone I’ve missed? What should I be looking out for? Or asking for? What pitfall am I about to step into? If you were doing this project, what would be your biggest concern?
Hope that all made sense and all expert replies gratefully received. I’m really keen to do this work (as you can imagine - going from two s
t spaces to one massive one is such a petrolhead opportunity) but if I accidentally collapse my house or do something stupid that’ll cost a fortune to resolve - I’ll kick myself (and the Mrs will join in!) Thank you!
(Recently retired Chartered Building Surveyor; our house has parts of the upper floor supported at various locations by 5 steel beams, all designed by a structural engineer but detailed by me).
When you say the engineer has designed the beams, have they also detailed how they sit within the structure? Both beams will be pretty chunky, given the spans involved. You say the integral garage sits mostly under the first floor; I’m visualising a small mono pitch roof over the front section?
- Will there in fact be a need to install two lateral beams (if my guess regarding the roof is correct): one supporting the first floor front wall and one the front of the roof over the garage door opening(s)? (On reflection, there would be a beam supporting the first floor already; has the way the outboard end will be picked up by the new longitudinal beam been detailed?)
- Given the age of the house, the single storey garage roof will probably be a gang nail truss structure; is there enough space to place the lateral beam beneath the trusses without reducing the height of the door openings? Trusses of this era will not take adaptation readily.
- be prepared for the room(s) above the garage to be disturbed and potentially need to be cleared for propping, installing beams etc..
When you say the engineer has designed the beams, have they also detailed how they sit within the structure? Both beams will be pretty chunky, given the spans involved. You say the integral garage sits mostly under the first floor; I’m visualising a small mono pitch roof over the front section?
- Will there in fact be a need to install two lateral beams (if my guess regarding the roof is correct): one supporting the first floor front wall and one the front of the roof over the garage door opening(s)? (On reflection, there would be a beam supporting the first floor already; has the way the outboard end will be picked up by the new longitudinal beam been detailed?)
- Given the age of the house, the single storey garage roof will probably be a gang nail truss structure; is there enough space to place the lateral beam beneath the trusses without reducing the height of the door openings? Trusses of this era will not take adaptation readily.
- be prepared for the room(s) above the garage to be disturbed and potentially need to be cleared for propping, installing beams etc..
Edited by Stegel on Thursday 16th January 22:29
Stegel said:
(Recently retired Chartered Building Surveyor; our house has parts of the upper floor supported at various locations by 5 steel beams, all designed by a structural engineer but detailed by me).
When you say the engineer has designed the beams, have they also detailed how they sit within the structure? Both beams will be pretty chunky, given the spans involved. You say the integral garage sits mostly under the first floor; I’m visualising a small mono pitch roof over the front section?
- Will there in fact be a need to install two lateral beams (if my guess regarding the roof is correct): one supporting the first floor front wall and one the front of the roof over the garage door opening(s)? (On reflection, there would be a beam supporting the first floor already; has the way the outboard end will be picked up by the new longitudinal beam been detailed?)
- Given the age of the house, the single storey garage roof will probably be a gang nail truss structure; is there enough space to place the lateral beam beneath the trusses without reducing the height of the door openings? Trusses of this era will not take adaptation readily.
- be prepared for the room(s) above the garage to be disturbed and potentially need to be cleared for propping, installing beams etc..
Brilliant, thanks so much for taking the time to answer - I’ll try to answer your questions but apologies if some of my terminology is off.. When you say the engineer has designed the beams, have they also detailed how they sit within the structure? Both beams will be pretty chunky, given the spans involved. You say the integral garage sits mostly under the first floor; I’m visualising a small mono pitch roof over the front section?
- Will there in fact be a need to install two lateral beams (if my guess regarding the roof is correct): one supporting the first floor front wall and one the front of the roof over the garage door opening(s)? (On reflection, there would be a beam supporting the first floor already; has the way the outboard end will be picked up by the new longitudinal beam been detailed?)
- Given the age of the house, the single storey garage roof will probably be a gang nail truss structure; is there enough space to place the lateral beam beneath the trusses without reducing the height of the door openings? Trusses of this era will not take adaptation readily.
- be prepared for the room(s) above the garage to be disturbed and potentially need to be cleared for propping, installing beams etc..
Edited by Stegel on Thursday 16th January 22:29
I think you’re spot on about the construction you’re picturing - yes, there’s a little mono pitch roof on the front, which sits on the lintels and courses of bricks that run across the top of the two doors and sits on the front pier. This is only supporting its own weight really - nothing to do with the first floor itself.
The engineer has thought about how they’ll sit, as you say. The upper surface of the new main front-to-back span RSJ will sit at the same level as the one it’s replacing (which currently only runs from the back of the garage to the pier in the middle of the garage). Effectively we’re extending the length of that RSJ but also making it much stronger and more substantial, but by projecting downwards and sideways rather than upwards. The pier at the rear is very large and he is confident is more than strong enough, but has allowed for the option to have another vertical steel put on the front of it, a new pad underneath, to add strength should they find anything undersized when they start taking it all apart.
The connections between the various beams have been detailed apart from the connection to the existing lateral beam that underpins the front of the first floor, because it’s currently all boxed in and fireproofed so hard to see without some brutal removal. He’s proposed the most obvious solution but there’s agreement between him and the contractor that they might have to adapt that plan once everything is fully exposed. Does that sound like a safe plan to you? They both seemed very comfortable with it.
Your question about the height of the big new longitudinal truss is a good one - I’ve looked at the plans and effectively what there today (a light lintel and a couple of courses of bricks on top) will be replaced by the RSJ which is substantially larger but by going up rather than down, then the brickwork fits inside the RSJ rather than on top. I hope that makes sense too.
I hadn’t thought about the need to empty out the room above - that’s a very good point. It’s a bedroom with a bunk bed and a typical ikea furniture but clearly that’s all unnecessary weight so I might need to move it out. Great catch, thank you!
MDifficult said:
Bingo, I end up with one massive double garage with a big single door and no pillar in the middle - so much room for activities!
The cost and complexity of putting an open space into an existing building.....Steels install and pad foundations are two things that gives me PTSD on our renovation project. Biggest worry was 'The lads keeps saying how complex the work is, what if they just don't turn up today'. Yours sound like it should be easier to do than ours, but don't underestimate the disruption it'll cause. It might be worthwhile thinking about just knocking down the old garage where you can and rebuilding it which might save you some steels/complexity.
With a been a 90s house you probably wouldn't/shouldn't come across any 'surprises'.
Good luck, it's a fun journey, your either really enjoy it, and come out of the other end wanting to change more of the house, or hate it, and never want to deal with builders every again
.
Edited by gangzoom on Friday 17th January 05:33
I am in the middle of having a new garage built that has significant steelwork needed, several on pad foundations against an existing wall, along with tying in to the exiting structure. We’ve also done various projects that have had existing structures extensively propped for new steel/oak to go in. What you’re doing wont sound anywhere near as daunting if you ever do it again.
Has anyone checked the weight of the beams, including any connections/plates, and confirmed how the builders are going to deal with them? If they’re experienced with steelwork they’ll have a plan, but if a Genie won’t cope and you end up needing a crane at any point, they generally charge by the day… circa £750 round us, but also introduces greater need to co-ordinate multiple parties to get the heavy steels off the delivery truck etc. It’s probably not a huge sum in the context of what’ll be spent but always nice to know what you’re in for.
The big steel across the top of the goalpost on ours is very deep. TRIPLE check headroom, especially on the front opening!
From a purely practical perspective, I’d prefer a new steel column at the back. You’ve then got the steel frame capable of being designed without needing to worry too much about the a new pier at the back.
Don’t forget that the steel may need painting. That adds in a bit of time/work to do. Steel fabricators may offer painting but none who have supplied us have been good…usually a quick blow over. Most recent ones were supplied primed and then painted on site.
If you’ve got invasive works taking place, and new foundations being dug in there, are you going to get the rest of the existing floor dug out and a new insulated slab put in?
Has anyone checked the weight of the beams, including any connections/plates, and confirmed how the builders are going to deal with them? If they’re experienced with steelwork they’ll have a plan, but if a Genie won’t cope and you end up needing a crane at any point, they generally charge by the day… circa £750 round us, but also introduces greater need to co-ordinate multiple parties to get the heavy steels off the delivery truck etc. It’s probably not a huge sum in the context of what’ll be spent but always nice to know what you’re in for.
The big steel across the top of the goalpost on ours is very deep. TRIPLE check headroom, especially on the front opening!
From a purely practical perspective, I’d prefer a new steel column at the back. You’ve then got the steel frame capable of being designed without needing to worry too much about the a new pier at the back.
Don’t forget that the steel may need painting. That adds in a bit of time/work to do. Steel fabricators may offer painting but none who have supplied us have been good…usually a quick blow over. Most recent ones were supplied primed and then painted on site.
If you’ve got invasive works taking place, and new foundations being dug in there, are you going to get the rest of the existing floor dug out and a new insulated slab put in?
It’s the pads that worry me, are you 100% sure there are no drains or utilities there, as they’ll probably need to go deeper than the house foundations due to the point load.
Also they will need to be fire protected as they support accommodation above? have you a detail for that, as they are likely to get damaged in a garage, so the usual 2 sheets of plasterboard won’t be any use, so you probably need intumescent paint, but applied by a specialist so you get a certificate. Given the extent and direct connection to ground, I’d get a 10mm earth connected to it back to the consumer unit and with all the PME faults at the moment, probably also bury an earth mat as well and connect at the bottom.
Also they will need to be fire protected as they support accommodation above? have you a detail for that, as they are likely to get damaged in a garage, so the usual 2 sheets of plasterboard won’t be any use, so you probably need intumescent paint, but applied by a specialist so you get a certificate. Given the extent and direct connection to ground, I’d get a 10mm earth connected to it back to the consumer unit and with all the PME faults at the moment, probably also bury an earth mat as well and connect at the bottom.
gangzoom said:
The cost and complexity of putting an open space into an existing building.....Steels install and pad foundations are two things that gives me PTSD on our renovation project. Biggest worry was 'The lads keeps saying how complex the work is, what if they just don't turn up today'.
Yours sound like it should be easier to do than ours, but don't underestimate the disruption it'll cause. It might be worthwhile thinking about just knocking down the old garage where you can and rebuilding it which might save you some steels/complexity.
With a been a 90s house you probably wouldn't/shouldn't come across any 'surprises'.
Good luck, it's a fun journey, your either really enjoy it, and come out of the other end wanting to change more of the house, or hate it, and never want to deal with builders every again.
Wow! Thankfully I think mine’s infinitely less complex than yours - what’s in those pictures would definitely keep me up at night! Yours sound like it should be easier to do than ours, but don't underestimate the disruption it'll cause. It might be worthwhile thinking about just knocking down the old garage where you can and rebuilding it which might save you some steels/complexity.
With a been a 90s house you probably wouldn't/shouldn't come across any 'surprises'.
Good luck, it's a fun journey, your either really enjoy it, and come out of the other end wanting to change more of the house, or hate it, and never want to deal with builders every again
.The thing is, knocking down and re-building the garage doesn’t really help as this isn’t really about the garage at all.. the garage is really just one load-bearing corner of the house and then the rest is single story brick walls that just support their own weight.
This is actually about the house.. it’s all about taking a single load-bearing column that holds up one corner of the first floor (that just happens to be in the middle of the garage) and moving that load to the end of the garage and down either side of the garage door to the floor. Sounds mad but this doesn’t really impact the garage at all (other than turning two doors into one)!
Thanks very much for the advice - I’ve backed away from doing this three times in the 15 years or so we’ve lived here specifically because of the stress of it
LooneyTunes said:
I am in the middle of having a new garage built that has significant steelwork needed, several on pad foundations against an existing wall, along with tying in to the exiting structure. We’ve also done various projects that have had existing structures extensively propped for new steel/oak to go in. What you’re doing wont sound anywhere near as daunting if you ever do it again.
Has anyone checked the weight of the beams, including any connections/plates, and confirmed how the builders are going to deal with them? If they’re experienced with steelwork they’ll have a plan, but if a Genie won’t cope and you end up needing a crane at any point, they generally charge by the day… circa £750 round us, but also introduces greater need to co-ordinate multiple parties to get the heavy steels off the delivery truck etc. It’s probably not a huge sum in the context of what’ll be spent but always nice to know what you’re in for.
The big steel across the top of the goalpost on ours is very deep. TRIPLE check headroom, especially on the front opening!
From a purely practical perspective, I’d prefer a new steel column at the back. You’ve then got the steel frame capable of being designed without needing to worry too much about the a new pier at the back.
Don’t forget that the steel may need painting. That adds in a bit of time/work to do. Steel fabricators may offer painting but none who have supplied us have been good…usually a quick blow over. Most recent ones were supplied primed and then painted on site.
If you’ve got invasive works taking place, and new foundations being dug in there, are you going to get the rest of the existing floor dug out and a new insulated slab put in?
Good luck with yours and thanks for the reply! Has anyone checked the weight of the beams, including any connections/plates, and confirmed how the builders are going to deal with them? If they’re experienced with steelwork they’ll have a plan, but if a Genie won’t cope and you end up needing a crane at any point, they generally charge by the day… circa £750 round us, but also introduces greater need to co-ordinate multiple parties to get the heavy steels off the delivery truck etc. It’s probably not a huge sum in the context of what’ll be spent but always nice to know what you’re in for.
The big steel across the top of the goalpost on ours is very deep. TRIPLE check headroom, especially on the front opening!
From a purely practical perspective, I’d prefer a new steel column at the back. You’ve then got the steel frame capable of being designed without needing to worry too much about the a new pier at the back.
Don’t forget that the steel may need painting. That adds in a bit of time/work to do. Steel fabricators may offer painting but none who have supplied us have been good…usually a quick blow over. Most recent ones were supplied primed and then painted on site.
If you’ve got invasive works taking place, and new foundations being dug in there, are you going to get the rest of the existing floor dug out and a new insulated slab put in?
The team who are doing the work seem very competent - they’re not general builders, they’re guys who put steelwork into existing houses day in, day out, so they have an experienced team and all the equipment - from the pictures I’ve seen my project seems like a walk in the park, so they give me confidence on that part. The largest span is about 5.2m and I’ve seen where they’ve dealt with more than double that easily.
However, you raise a point that IS eating at my paranoia a bit. Fire protection, water/rust protection, painting/galvanising etc, especially as the two vertical columns either side of the goalpost will both be somewhat exposed to the elements as they’re on the front of the house and will go onto the new sunken pads and then be covered over to level up to the floor..
As far as I understand it, this is all covered by building regulations, but it’s the area I’m least clear on and plan to discuss at length with the contractor at the next chat, but any thoughts gratefully received!
Rough101 said:
It’s the pads that worry me, are you 100% sure there are no drains or utilities there, as they’ll probably need to go deeper than the house foundations due to the point load.
Also they will need to be fire protected as they support accommodation above? have you a detail for that, as they are likely to get damaged in a garage, so the usual 2 sheets of plasterboard won’t be any use, so you probably need intumescent paint, but applied by a specialist so you get a certificate. Given the extent and direct connection to ground, I’d get a 10mm earth connected to it back to the consumer unit and with all the PME faults at the moment, probably also bury an earth mat as well and connect at the bottom.
Hi, thanks so much for replying! Also they will need to be fire protected as they support accommodation above? have you a detail for that, as they are likely to get damaged in a garage, so the usual 2 sheets of plasterboard won’t be any use, so you probably need intumescent paint, but applied by a specialist so you get a certificate. Given the extent and direct connection to ground, I’d get a 10mm earth connected to it back to the consumer unit and with all the PME faults at the moment, probably also bury an earth mat as well and connect at the bottom.
We’re not 100% sure about drains/utilities but pretty confident. The pads will be roughly 1m3 but one is actually slightly larger and offset in order to have a big margin to where we know the gas main comes in. Is there any real cost effective way to be more confident other than picking up a shovel and having a look? That’s a genuine question
Again, fire protection, paint, earthing, excellent questions.. I’m unclear about whose responsibility that is. Doesn’t seem like a structural engineer question, so I’m guessing it sits with the contractors and I should discuss and clarify with them as they’re responsible for meeting building regs?
Thanks again for the help!
If they do structural steelwork day after day it should be a walk in the park. Pad foundations aren’t overly stressful when all goes according to plan, but if you’re concerned just have them made larger, stronger concrete, more fabric.
We’ve had some jobs with galvanised steel (overkill in many situations) but most on this job are painted. A properly applied paint can give a maintenance life of 15 years in an exposed setting.
MDifficult said:
However, you raise a point that IS eating at my paranoia a bit. Fire protection, water/rust protection, painting/galvanising etc, especially as the two vertical columns either side of the goalpost will both be somewhat exposed to the elements as they’re on the front of the house and will go onto the new sunken pads and then be covered over to level up to the floor..
Rust is oxidisation of the steel. Once the bases are encased in concrete there won’t be anything getting to them… The SE/building regs docs should stipulate any treatment needed. We’ve had some jobs with galvanised steel (overkill in many situations) but most on this job are painted. A properly applied paint can give a maintenance life of 15 years in an exposed setting.
Nothing to add except it’s well worth doing.
1970s bungalow here with the central pier removed about 20-25 years ago to create one 4.5m wide double door instead of two singles. There is one I beam across the span on the inner leaf of brickwork, with the rafters sat on it. No piers, goal posts or other steels but all it’s holding up is the lower bit of roof over the garage from mid span purlins downwards.
It’s not moved, not rusted, and makes the garage massively more usable, in fact due to the angle of the drive I don’t think I’d get a car in at all if it was still two single doors.
Do it!
1970s bungalow here with the central pier removed about 20-25 years ago to create one 4.5m wide double door instead of two singles. There is one I beam across the span on the inner leaf of brickwork, with the rafters sat on it. No piers, goal posts or other steels but all it’s holding up is the lower bit of roof over the garage from mid span purlins downwards.
It’s not moved, not rusted, and makes the garage massively more usable, in fact due to the angle of the drive I don’t think I’d get a car in at all if it was still two single doors.
Do it!
MDifficult said:
Brilliant, thanks so much for taking the time to answer - I’ll try to answer your questions but apologies if some of my terminology is off..
I think you’re spot on about the construction you’re picturing - yes, there’s a little mono pitch roof on the front, which sits on the lintels and courses of bricks that run across the top of the two doors and sits on the front pier. This is only supporting its own weight really - nothing to do with the first floor itself.
The engineer has thought about how they’ll sit, as you say. The upper surface of the new main front-to-back span RSJ will sit at the same level as the one it’s replacing (which currently only runs from the back of the garage to the pier in the middle of the garage). Effectively we’re extending the length of that RSJ but also making it much stronger and more substantial, but by projecting downwards and sideways rather than upwards. The pier at the rear is very large and he is confident is more than strong enough, but has allowed for the option to have another vertical steel put on the front of it, a new pad underneath, to add strength should they find anything undersized when they start taking it all apart.
The connections between the various beams have been detailed apart from the connection to the existing lateral beam that underpins the front of the first floor, because it’s currently all boxed in and fireproofed so hard to see without some brutal removal. He’s proposed the most obvious solution but there’s agreement between him and the contractor that they might have to adapt that plan once everything is fully exposed. Does that sound like a safe plan to you? They both seemed very comfortable with it.
Your question about the height of the big new longitudinal truss is a good one - I’ve looked at the plans and effectively what there today (a light lintel and a couple of courses of bricks on top) will be replaced by the RSJ which is substantially larger but by going up rather than down, then the brickwork fits inside the RSJ rather than on top. I hope that makes sense too.
I hadn’t thought about the need to empty out the room above - that’s a very good point. It’s a bedroom with a bunk bed and a typical ikea furniture but clearly that’s all unnecessary weight so I might need to move it out. Great catch, thank you!
It sounds like you have all points covered, and have the right people involved, albeit the issue of any services in the way of the new pads, as raised below, is something to be aware of; diverting drains would be a real nuisance. I would knock a hole in the fire protection a week before work starts just so everyone can see what splice plates, what holes need drilling or beam shortened, etc. are required in advance. I think you’re spot on about the construction you’re picturing - yes, there’s a little mono pitch roof on the front, which sits on the lintels and courses of bricks that run across the top of the two doors and sits on the front pier. This is only supporting its own weight really - nothing to do with the first floor itself.
The engineer has thought about how they’ll sit, as you say. The upper surface of the new main front-to-back span RSJ will sit at the same level as the one it’s replacing (which currently only runs from the back of the garage to the pier in the middle of the garage). Effectively we’re extending the length of that RSJ but also making it much stronger and more substantial, but by projecting downwards and sideways rather than upwards. The pier at the rear is very large and he is confident is more than strong enough, but has allowed for the option to have another vertical steel put on the front of it, a new pad underneath, to add strength should they find anything undersized when they start taking it all apart.
The connections between the various beams have been detailed apart from the connection to the existing lateral beam that underpins the front of the first floor, because it’s currently all boxed in and fireproofed so hard to see without some brutal removal. He’s proposed the most obvious solution but there’s agreement between him and the contractor that they might have to adapt that plan once everything is fully exposed. Does that sound like a safe plan to you? They both seemed very comfortable with it.
Your question about the height of the big new longitudinal truss is a good one - I’ve looked at the plans and effectively what there today (a light lintel and a couple of courses of bricks on top) will be replaced by the RSJ which is substantially larger but by going up rather than down, then the brickwork fits inside the RSJ rather than on top. I hope that makes sense too.
I hadn’t thought about the need to empty out the room above - that’s a very good point. It’s a bedroom with a bunk bed and a typical ikea furniture but clearly that’s all unnecessary weight so I might need to move it out. Great catch, thank you!
Clearing the room above is sensible; it’s not the weight, it’s working space; the contractor may need to needle through above floor level to allow the existing beam to be removed. You will be decorating and making good in there.
I would just use plasterboard to protect the new steels from fire. Application of intumescent paint is a specialist job - the thickness required varies with section size and weight - and there can be issues with compatibility of primer etc.. It will be far cheaper to just board them out, and the stanchions will then be protected from scuffing, and present a more friendly surface for car door edges etc..
ETA: and as above, don’t worry about corrosion of the steels; if they’re rusting you have far greater issues!
Edited by Stegel on Friday 17th January 08:59
Nothing particularly complex here, providing the contractor knows what they're doing.
The propping strategy is key, and I'd ensure your chosen engineer has both considered this, and validated the contractors proposal. Given the length of the main steel, some pre-cambering may also be applied to reduce overall deflection. The detailing of the connections also makes a difference; again make sure your SE has either designed these themselves, or ok'd the steelwork fabricators drawings.
The propping strategy is key, and I'd ensure your chosen engineer has both considered this, and validated the contractors proposal. Given the length of the main steel, some pre-cambering may also be applied to reduce overall deflection. The detailing of the connections also makes a difference; again make sure your SE has either designed these themselves, or ok'd the steelwork fabricators drawings.
It sounds to me like you have employed a suitable designer and contractor and considered the key issues, other than perhaps services, which it would be worth exporing further as could lead to significant delay and additional cost.
The only other thing I’d mention would be consider design liability - the nature of such works can often involve ad hoc changes during install - if these are being suggested by the contractor then you either need to be confident that they are accepting design liability (and have adequate PI insurance) or they need to be co-ordinated with the engineer and agreed - not always easy when you have a load of guys stood around and, in my experience, SEs seem to have an aversion to visiting site
The only other thing I’d mention would be consider design liability - the nature of such works can often involve ad hoc changes during install - if these are being suggested by the contractor then you either need to be confident that they are accepting design liability (and have adequate PI insurance) or they need to be co-ordinated with the engineer and agreed - not always easy when you have a load of guys stood around and, in my experience, SEs seem to have an aversion to visiting site
Timbo_S2 said:
Cow Corner said:
SEs seem to have an aversion to visiting site
No-one wants to pay for them to do so, and if its D&B the Contractor doesn't like them pointing out everything they've built incorrectly... ) but mainly there to help the OP understand the risks in ad hoc design changes.LooneyTunes said:
Rust is oxidisation of the steel. Once the bases are encased in concrete there won’t be anything getting to them… The SE/building regs docs should stipulate any treatment needed.
We’ve had some jobs with galvanised steel (overkill in many situations) but most on this job are painted. A properly applied paint can give a maintenance life of 15 years in an exposed setting.
Very helpful - thank you! We’ve had some jobs with galvanised steel (overkill in many situations) but most on this job are painted. A properly applied paint can give a maintenance life of 15 years in an exposed setting.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff