How to fix insulation to porch ceiling

[PeteThePen1]

Godd Afternoon Everybody

Our dreadful 1930 house has the front cantilevered out over the ground floor by about 1m. Part of that is filled by the bay window and the rest just hangs out or forms the porch over the front door. Having found no way to get into the floor space that hangs out (practical and political) the sensible soultion would seem to be to stick Kingspan to the underside of the hangout. There is sufficient 'depth' for 150mm. I carefully measured it all, drawin it in CAD and was amused to find that it needs just one sheet of Kingspan and one sheet of exterior grade ply. That will be painted white to give the same appearance as now.

We suspect that the existing 'ceiling' and the left side trim are probably asbestos board. Thus the principal fixing method will be a grab adhesive like Stick Like Sh*t. We are proposing to stick the plywood to the Kingspan when that is fixed and to trim the edges with 20mm quarter round beading. To fix that am proposing to hire a nailgun and get some 30mm stainless nails (I don't know if my builder has such a gun). My thoughts are that doing that will not release any fibres from the asbestos board. The side on the house could be screwed as that has a wooden trim plank.

Thus the question is "How many tubes of grab adhesive will be needed?". A second question is whether this is a sensible approach. My builder agrees that sticking it up with adhesive seems sensible but you folks may have a better solution.

Many thanks

Pete

 

[blup]

CT1 might be a better sealant/adhesive. Or do an asbestos test, if all clear use hole saw and blow loose insulation in.

Blup

 

[kingandy2nd]

I’d just work out where the joists are and use some 200mm screws to fix it

 

[PeteThePen1]

Hi Folks

Many thanks for your replies and apologies for not posting any sooner. That Festive Fortnight rather gets in the way of DIY projects.

The project so far has had a reply from C-Tec Technical Services, the folks that make CT1 but who also make Power Grab ‘n’ Bond which is an even more 'aggressive' adhesive. They report that the stuff would easily hold the Kingspan board and plywood but only if the substrate is secure. They epressed worry that if it was oil painted then the paint could detatch from the substrate or possiby that the paint might be the sort for which Power Grab ‘n’ Bond might be reflected off (although it might seem to adhere when initially pressed into position).

That brings us to the suggestion of long screws. I have now discovered that there is a wealth of long screws in both steel and A2 if one does a little bit of internet searching (our local stores don't go above 50mm). There is a clear joist at the point where the former porch light was fitted. That I can see because there is a hole in the covering material. What I can also see is that laths have been used to support the covering material which might suggest some form of plaster. I say that because all the non load bearing walls in the house are lath and plaster.

That brings is to the question of what exactly is the material covering the joists? Given the hole where the light wiring comes through, it has been possible to get a small sample. I have sent for a kit from Asbestos Kits UK (https://asbestoskits.co.uk/) and have with considerable cution taken a sample according to their instructions and popped it into the post. I am hoping for a decision on the asbestos or not issue next week.

The final task has been to try to find where the joists are besides the one next to the light fitting. Elsewhere in the house they are spaced at 16" centres (very approximately!) so I have marked off where they could be if that is the case here. Of course the positions do not make sense as the final one at the east end is ony 8" from the end of the porch. I fear that they may simply have spaced a given number of short joists evenly across the space. So when I know what the current covering is made from I think some exploratory holes will be called for.

Regards

Pete

 

[geraldthehamster]

Drilling a few holes through asbestos cement board won't kill you. Wear a mask against dust