Recommended Length of Mushroom Fixings for 62.5 mm Sheets

I used 8 x 110 mm for the kitchen, but the render and plaster was fairly shallow. On the old part of the house, the render is quite thick, 1/2 inch in places and crumbly. So after the fixing goes through the sheet and render, there's about 35 mm in "solid concrete", but the end of the fixing is tapered, so probably only 25 inch holding. Probably better to go for 8 x 140s? I was able to pull two of the fixings out after hammering in. Possibly cavities in the shuttered concrete walls, bad concrete or spots where the render was extra thick.
 

bof

Well-Known Member
I used 8 x 110 mm for the kitchen, but the render and plaster was fairly shallow. On the old part of the house, the render is quite thick, 1/2 inch in places and crumbly. So after the fixing goes through the sheet and render, there's about 35 mm in "solid concrete", but the end of the fixing is tapered, so probably only 25 inch holding. Probably better to go for 8 x 140s? I was able to pull two of the fixings out after hammering in. Possibly cavities in the shuttered concrete walls, bad concrete or spots where the render was extra thick.
Sorry its late , I'm assuming that you are fixing foam backed plasterboard , you are sticking them to skimmed render and these are fire fixings your on about , sorry can you clarify mate
 

essexandy

The Lake Governor
Sorry its late , I'm assuming that you are fixing foam backed plasterboard , you are sticking them to skimmed render and these are fire fixings your on about , sorry can you clarify mate
He's talking about external insulation mate.
 
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Sorry its late , I'm assuming that you are fixing foam backed plasterboard , you are sticking them to skimmed render and these are fire fixings your on about , sorry can you clarify mate
Yes, insulation backed plasterboard panels. I'm fixing them to shuttered concrete walls with metal mushrooms.
(sorry I'm calling the cement skim under the plaster "render", probably not the right term. Why would they cement over shuttered concrete? The concrete should be relatively smooth since it was cast between plywood sheets (80 years ago).
 

bof

Well-Known Member
Yes, insulation backed plasterboard panels. I'm fixing them to shuttered concrete walls with metal mushrooms.
(sorry I'm calling the cement skim under the plaster "render", probably not the right term. Why would they cement over shuttered concrete? The concrete should be relatively smooth since it was cast between plywood sheets (80 years ago).
So are you sticking the boards or just screwing
 
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