Fixing wood to thin outer wall

phil675

phil675

phil675

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Joined
15 Jan 2005
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UK
Hi,

I want to attach a plank of wood to a pebbledash wall for a lean-to. As the inside walls of the house are difficult to drill through, I assumed it would be a pain to go from the outside too. To my surprise the corded non-SDS drill went through quite quickly, there is some soft stuff that goes as long as the drill bit and then another solid wall which must be inside.

So I try one of the thunderbolt screws I had bought anyway and there isn't much for the screw threads to grip into, so they're out. I have some bolts like this:

But if the end that gets pulled up is just in the cavity I'm guessing that won't do much either? What's the best thing to do here? I don't know if plasterboard fixings will be appropriate.

Many thanks.
 
I have a similar situation in my bedroom. I use an 8mm fischer wall plug and then whack a 6mm plug inside of that.
 
phil675 said:
Hi,

I want to attach a plank of wood to a pebbledash wall for a lean-to. As the inside walls of the house are difficult to drill through, I assumed it would be a pain to go from the outside too. To my surprise the corded non-SDS drill went through quite quickly, there is some soft stuff that goes as long as the drill bit and then another solid wall which must be inside.

So I try one of the thunderbolt screws I had bought anyway and there isn't much for the screw threads to grip into, so they're out. I have some bolts like this:

But if the end that gets pulled up is just in the cavity I'm guessing that won't do much either? What's the best thing to do here? I don't know if plasterboard fixings will be appropriate.

Many thanks.
Click to expand...
What was the depth of the outer wall? I’ll guess at 4” so assuming your expansion bolt is also 4” long you’ll be fine.
 
phil675 said:
More like half an inch.
Click to expand...
Sorry. You’re saying that the outside wall of your house are only half an inch thick? Are you describing it correctly? Where are you trying to fix a piece of baton too? Pebbledash had me assuming it’s to the outside of your house.
 
Doobedoo said:
Sorry. You’re saying that the outside wall of your house are only half an inch thick? Are you describing it correctly? Where are you trying to fix a piece of baton too? Pebbledash had me assuming it’s to the outside of your house.
Click to expand...

Yes its outside. I drill with a usual diy length 10mm bit, through it goes after a short distance and I hit another wall after a long gap, almost the entire drill bit can get in. There is something in there giving squishy resistance like insulation.
 
sounds like your property has had external insulation installed and then been rendered/pebble dashed to seal it. if this is the case just above ground level there will be a step out to the render from the original walls.
 
phil675 said:
Yes its outside. I drill with a usual diy length 10mm bit, through it goes after a short distance and I hit another wall after a long gap, almost the entire drill bit can get in. There is something in there giving squishy resistance like insulation.
Click to expand...
How long is your drill bit?
 
You need to better understand the construction of the wall. If it's render sat on insulation or similar you could easily crack the render by putting pressure on it and crushing the insulation. Either when tightening the fixings or from the lean-to pushing against the wall.
 
Doobedoo said:
How long is your drill bit?
Click to expand...

10-15cm

Abyss said:
You need to better understand the construction of the wall. If it's render sat on insulation or similar you could easily crack the render by putting pressure on it and crushing the insulation. Either when tightening the fixings or from the lean-to pushing against the wall.
Click to expand...

This is turning out to be a bit of a pain, the original plan was to put posts by the wall instead but the concrete path there is not very thick either and there is a gap to the soil below, god knows how it hasn't cracked for all this time, but I cant secure a fence post to the ground by the wall either.
 
Personally I would gauge how far I’ve drilled into a solid wall beneath all the insulation l, so if I drill 6-7 inches through render, insulation and then solid wall. Id then buy the relevant length through bolts tap em in then tighten them up.

You shouldn’t need to tighten too much so no risk if crushing render etc.

https://www.screwfix.com/p/rawlplug-xpt-throughbolts-m12-x-180mm-10-pack/87397
 
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