Hi, hoping someone will be able to help . We’re building a pergola, 7m x 3m. It’ll be attached to the house and the will have 6 cross beams and 4 posts across the front (if that makes sense). My question is this, we have a patio that’s already there and when we’ve drilled down to anchor the posts there’s no concrete. My husband read that you can pump resin in to create a foundation to secure the bolts into? My concern is that in high winds it may snap the slate patio slab, cause damage to the house as it lifts or move the pergola. Am I right in thinking we actually need to make a proper concrete foundation? Any help would be appreciated, thank you
That’s a bit sad. No way are you going to be able to just drill holes through the slate slabs which appear to only be bedded on sand or other soft material and inject resin. It just wouldn’t hold. Did you just hit s soft spot with the drill I wonder, would be worth trying another hole or two. Think this is s case of lifting the slabs where the posts will go, digging out and pouring in say 450 by 450 by 300 concrete and resetting the slabs onto that.
Do you have a picture of what you want and the rough sizes of the timber. Depending on the design and the weight there are other solutions from just standing the uprights on a slab to fitting metal post legs which are a single rod with a U bracket on the top to hold the post
The posts are, 100x100x2700mm The cross beams are, 47x150 I can’t find the original drawing so I’ve drawn what it’ll look.... not the best sketch.
Tim If your attaching it to the house whats the problem. Drill slabs & place "Post Feet" onto slab. This will stabilize the posts and then fix to wall. It shouldn't go anywhere. Dont forget a few bracer bars to posts. Use same size timber.
Much as above use the post feet. I would give them a coat of paint first, it is much easier now than later. Also shop around as the prices vary a lot especially between the two type - clamp and screw tight. And as said above plenty of braces to stop it moving. You may find it easier and better to use joist hangers for the timber where it joins the wall. https://www.screwfix.com/p/sabrefix-mini-hanger-50-x-65mm-10-pack/63868
Just finished painting the wood and sorting the braces. Will fit it all together during the week. Thank you for all your help it’s appreciated.
Tim, after all the work we have done here, I would like to think you would post up some pictures for us to see. If you have any problems fitting up, you know where to come.
As your pergola is being fixed to the house, the uprights on the patio just need securing against sideways movement if knocked. What I have done in the past is get a length of 10mm stainless stud bar and hammer it down through a 10mm hole in the slab into the ground below. With a couple of nuts and large washers screwed down onto the slab, you can drill a deep hole in your post and slip it over the stud bar that is sticking up. It will stand a few mm above the slab (thickness of nuts washers), keeping the foot of the post dry, and the stud bar will provide a firm anchorage against sideways movement.
Hi.. little late to this one but hopefully will be adding a pergola to our shed this spring..mounted off the shed in the same way yours is mounted off your house. How deep did you need to go inorder to anchor those concealed post into the slab & ground??
That looks nice. Can you stand on it to clean the first floor windows. Which direction does your garden face ?