Aluminium Pergola Bolt Down
Discussion
I've built up a Pergolux Pergola which is 3 wide. My patio is 3m wide. Patio is granite slabs on full mortar bed.
My problem is that the bolt down holes for pergola on the "feet" extend just beyond the patio and beyond the 3m. So the 12mm hole is almost in line with the patio edge and bolt would slide down past the patio edge and the mortar bed it sits on. I can make a concrete pad at the side of the patio but I'd be bolting right at the edge of the concrete pad.
Nice little diagram here which probably helps explain the foot : https://pergolux.co.uk/products/pergolux-pergola-s...
Best plan I can come up with is 12mm stainless steel threaded rods with 50mm square washers and put these in place into a hole (maybe 200 x 200 x 150 deep) which I then fill in with concrete to make a pad. Once the concrete has set the square washer and the rod would be pretty well stuck in the concrete albeit right at the edge of it. The square washer would go under patio by a few mm and be well into the bottom of the concrete pad.
Does that basically seem ok or some other idea? Nothing I can think of seems ideal. The pergola is not massively exposed to the wind and will have glass on the main wall that is.
I've seen other ideas like filling planters partly with concrete and bolting that to it but not great.
Cheers!
My problem is that the bolt down holes for pergola on the "feet" extend just beyond the patio and beyond the 3m. So the 12mm hole is almost in line with the patio edge and bolt would slide down past the patio edge and the mortar bed it sits on. I can make a concrete pad at the side of the patio but I'd be bolting right at the edge of the concrete pad.
Nice little diagram here which probably helps explain the foot : https://pergolux.co.uk/products/pergolux-pergola-s...
Best plan I can come up with is 12mm stainless steel threaded rods with 50mm square washers and put these in place into a hole (maybe 200 x 200 x 150 deep) which I then fill in with concrete to make a pad. Once the concrete has set the square washer and the rod would be pretty well stuck in the concrete albeit right at the edge of it. The square washer would go under patio by a few mm and be well into the bottom of the concrete pad.
Does that basically seem ok or some other idea? Nothing I can think of seems ideal. The pergola is not massively exposed to the wind and will have glass on the main wall that is.
I've seen other ideas like filling planters partly with concrete and bolting that to it but not great.
Cheers!
To help, I am making an educated guess at your suggested 200 x 200 x 150 giving you about 14kg of weight to hold down what looks like a fairly large "sail" would not take much wind to get under that and lift it.
I would go a lot bigger, and once it's set then secure the legs to it with threaded rod and epoxy to ensure you get a robust and importantly the rods in the correct place.
I would go a lot bigger, and once it's set then secure the legs to it with threaded rod and epoxy to ensure you get a robust and importantly the rods in the correct place.
Cheers both, appreciate not a great one but I have what I have.
it was this kind of padstone I was going to "self cast" around the rod and square washer with some shuttering. The rod would be trapped between new concrete and the patio (which is very solid) with square washer at bottom of the rod under my new concrete.
https://www.hughesforrest.com/concrete-padstone-44...
This is 22Kg. I'll double that in depth and go about 40kg total?
I can't resin in to anything as I'm beyond end of the patio and would be right at edge of pad I create too - drilling wouldn't really work - I think better I put concrete in wet and let it set around the fixings?
it was this kind of padstone I was going to "self cast" around the rod and square washer with some shuttering. The rod would be trapped between new concrete and the patio (which is very solid) with square washer at bottom of the rod under my new concrete.
https://www.hughesforrest.com/concrete-padstone-44...
This is 22Kg. I'll double that in depth and go about 40kg total?
I can't resin in to anything as I'm beyond end of the patio and would be right at edge of pad I create too - drilling wouldn't really work - I think better I put concrete in wet and let it set around the fixings?
The threaded rod with nuts + washers idea isn't bad if you want it to retain well into concrete; add more than one along the length, and not right at the bottom end. Assume you intend A4 stainless rod?
I wouldn't worry too much about the mass of the anchor; if it's buried there are more things involved than just the weight as anyone who's tried pulling out a fence post will know.
Personally I'd think about digging a reasonably deep hole (500mm minimum?) but not necessarily too wide (100/150mm?), and have it go slightly diagonally so it end up under the slab - so you'll have to bend the rod to get the tops into the necessary positions. That way it won't easily pull out and can take advantage of the slab to retain it. Basically position it so whichever direction the thing tries to lift it will be trying to pull the rod against/through the patio slab.
Add postcrete around the rods as this is the easiest thing to use & goes in dry so settles well. Put the pergola in place first (suitably held down!) so you're sure the anchors will be in the right places as it'd be fun trying to adjust them later.
Postcrete doesn't need to come too near the surface as it's an anchor and the embedded rod won't care about being exposed, so cosmetically it can stay as grass/soil and not a lump of bare concrete.
I wouldn't worry too much about the mass of the anchor; if it's buried there are more things involved than just the weight as anyone who's tried pulling out a fence post will know.
Personally I'd think about digging a reasonably deep hole (500mm minimum?) but not necessarily too wide (100/150mm?), and have it go slightly diagonally so it end up under the slab - so you'll have to bend the rod to get the tops into the necessary positions. That way it won't easily pull out and can take advantage of the slab to retain it. Basically position it so whichever direction the thing tries to lift it will be trying to pull the rod against/through the patio slab.
Add postcrete around the rods as this is the easiest thing to use & goes in dry so settles well. Put the pergola in place first (suitably held down!) so you're sure the anchors will be in the right places as it'd be fun trying to adjust them later.
Postcrete doesn't need to come too near the surface as it's an anchor and the embedded rod won't care about being exposed, so cosmetically it can stay as grass/soil and not a lump of bare concrete.
JoshSm said:
The threaded rod with nuts + washers idea isn't bad if you want it to retain well into concrete; add more than one along the length, and not right at the bottom end. Assume you intend A4 stainless rod?
I wouldn't worry too much about the mass of the anchor; if it's buried there are more things involved than just the weight as anyone who's tried pulling out a fence post will know.
Personally I'd think about digging a reasonably deep hole (500mm minimum?) but not necessarily too wide (100/150mm?), and have it go slightly diagonally so it end up under the slab - so you'll have to bend the rod to get the tops into the necessary positions. That way it won't easily pull out and can take advantage of the slab to retain it. Basically position it so whichever direction the thing tries to lift it will be trying to pull the rod against/through the patio slab.
Add postcrete around the rods as this is the easiest thing to use & goes in dry so settles well. Put the pergola in place first (suitably held down!) so you're sure the anchors will be in the right places as it'd be fun trying to adjust them later.
Postcrete doesn't need to come too near the surface as it's an anchor and the embedded rod won't care about being exposed, so cosmetically it can stay as grass/soil and not a lump of bare concrete.
Yes to stainless steel rod and I can add more nuts and washers to make it more "stuck". I will struggle with 500mm deep without making a massive mess due to large rocks in our ground and restricted access but will go a little wider if needed to compensate. I have gravel around it so ideally will try to keep this all hidden under that. I might be lucky with one footing and some old buried concrete I can fix into.I wouldn't worry too much about the mass of the anchor; if it's buried there are more things involved than just the weight as anyone who's tried pulling out a fence post will know.
Personally I'd think about digging a reasonably deep hole (500mm minimum?) but not necessarily too wide (100/150mm?), and have it go slightly diagonally so it end up under the slab - so you'll have to bend the rod to get the tops into the necessary positions. That way it won't easily pull out and can take advantage of the slab to retain it. Basically position it so whichever direction the thing tries to lift it will be trying to pull the rod against/through the patio slab.
Add postcrete around the rods as this is the easiest thing to use & goes in dry so settles well. Put the pergola in place first (suitably held down!) so you're sure the anchors will be in the right places as it'd be fun trying to adjust them later.
Postcrete doesn't need to come too near the surface as it's an anchor and the embedded rod won't care about being exposed, so cosmetically it can stay as grass/soil and not a lump of bare concrete.
Going diagonally and bending rod a little a good idea - I won't bend it much but will try to do that.
I've been thinking same to get pergola exactly where it's to go with rods etc. in place and then add the concrete or postcrete.
All really helpful thanks and a bit of a sanity check! It's a bit of a PITA and fair bit of work so rather get it right.
On a related note one thing I've done is keep some of my old brake disks for anchors, especially as temporary ones; as they're big old Brembos they're 15Kg each, nice & flat, and have handy holes already in them.
If they were buried deep enough they'd take some real effort to shift.
Amazing how often they've come in useful for holding stuff down.
If they were buried deep enough they'd take some real effort to shift.
Amazing how often they've come in useful for holding stuff down.
What size are the legs?
I used these: https://www.toolstation.com/post-base/p29420 to stop my log store (not massively different to a pergola) from shifting on its pad.
ETA: We bolted down with 10mm concrete bolts, approx 120mm IIRC. In your case it wouldn't hurt to lift a slab or two at each corner to add more concrete below them to provide a more secure anchor.
I used these: https://www.toolstation.com/post-base/p29420 to stop my log store (not massively different to a pergola) from shifting on its pad.
ETA: We bolted down with 10mm concrete bolts, approx 120mm IIRC. In your case it wouldn't hurt to lift a slab or two at each corner to add more concrete below them to provide a more secure anchor.
Edited by LooneyTunes on Monday 19th May 13:56
JoshSm said:
On a related note one thing I've done is keep some of my old brake disks for anchors, especially as temporary ones; as they're big old Brembos they're 15Kg each, nice & flat, and have handy holes already in them. If they were buried deep enough they'd take some real effort to shift.
What an excellent idea (as long as you don't run them too thin before they are replaced.)What I've done in the past (not for a Pergola) is to take two long lengths of threaded stainless steel rod and bang them into the hole at a shallowish angle, one going one way and one the other. I did this after digging the hole, but before pouring in concrete. That way, when the concrete sets it's also conjoined with these two steel anchors that go much deeper into the ground. Not sure I've explained it very well, but hopefully you get what I'm trying to say.
I took a look at the installation video for that and was thinking - could you re-orientate the square pad that's bolted into the leg to suit?
PS. if it's just the one fixing bolt that's the issue I wouldn't worry about it'll be fine with just two or you could drill an extra hole in the base plates and have three in line?
PS. if it's just the one fixing bolt that's the issue I wouldn't worry about it'll be fine with just two or you could drill an extra hole in the base plates and have three in line?
Thanks again all.
I can't move the plate but I could (probably) drill at least one new hole. The aluminum is so soft I'd worry about weakening it too much if I mess up!
I've ordered A4 stainless steel rods and will bend these slightly so I can get these at an angle then surround with concrete + at plate washers.
It means I can avoid drilling the granite patio too which was really expensive and large slabs.
Digging the holes be the challenge!
I can't move the plate but I could (probably) drill at least one new hole. The aluminum is so soft I'd worry about weakening it too much if I mess up!
I've ordered A4 stainless steel rods and will bend these slightly so I can get these at an angle then surround with concrete + at plate washers.
It means I can avoid drilling the granite patio too which was really expensive and large slabs.
Digging the holes be the challenge!
I thought that the crank in the rod was the best idea. I'd want a 500mm cube lump of concrete which should cover all eventualities but it depends on the ground and the pation construction. Can't you get some of the concrete cube/blob below the patio? The s/s rod should be in the centre of the concrete; if the concrete cube/blob is all outside the patio then a 45 degree crank in the s/s rod will allow it to go through the hole with a nut attached then the angled bit os the s/s rod will be securely anchored in the concrete.
TA14 said:
I thought that the crank in the rod was the best idea. I'd want a 500mm cube lump of concrete which should cover all eventualities but it depends on the ground and the pation construction. Can't you get some of the concrete cube/blob below the patio? The s/s rod should be in the centre of the concrete; if the concrete cube/blob is all outside the patio then a 45 degree crank in the s/s rod will allow it to go through the hole with a nut attached then the angled bit os the s/s rod will be securely anchored in the concrete.
Thanks for this, much appreciated!I'm hoping to dig a little under the mortar bed patio is on and bend the stainless out a bit so concrete blob is well around the rod. Doesn't seem great idea to bend stainless rods too much without a lot of heat from some quick reading so will go easy.
I think if wind force was high enough the aluminium tab I'm bolting through would snap before it would lift the concrete from the ground. The aluminium doesn't seem that strong.
KTMsm said:
Would a screw pile work ?
Generally used to support loads pushing down but would equally work the other way
I believe small DIY versions are available
Our ground is full of stone so I don't think so. If I could be sure of the size of stone I was hitting I could probably bolt it to some of those! Thanks.Generally used to support loads pushing down but would equally work the other way
I believe small DIY versions are available
orbit123 said:
KTMsm said:
Would a screw pile work ?
Generally used to support loads pushing down but would equally work the other way
I believe small DIY versions are available
Our ground is full of stone so I don't think so. If I could be sure of the size of stone I was hitting I could probably bolt it to some of those! Thanks.Generally used to support loads pushing down but would equally work the other way
I believe small DIY versions are available
dickymint said:
If I've got this right you are concerned about 2 of the 4 legs having only 2 bolts instead of 3? If so you are massively overthinking this unless you're living in hurricane alley
I wish that was case - I'm concerned about 4 of the legs having 0 bolts instead of 3 bolts 
The challenge is where the bolt holes land but I now have a good plan to solve.
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