Adding more insulation board to walls and ceilings

[Conor]

Hi, about 15 years ago I moved into an old stone cottage with a concrete extension. There was no insulation, I was working on the whole house so had to stretch my budget and only put int 25mm insulation backed plasterboard on all the external walls and ceilings, along with some loft insulation where I could get it.

Clearly this is not as much insulation as would be ideal. I'm now looking to add more. My initial thought is to get 75mm kingspan style boards add on top of the current boards and then add plasterboard.

There will be a few areas by windows, doors and the large fireplace where this is not possible. Is there a way of figuring out how effective the insulation will be when considering the cold bridges left in areas by the windows? I would hate to put in all the work and effort, reduce the size of the rooms and then find it's not really any better.

Techniques for attaching kingspan to insulated plasterboard walls and then plasterboard on top?

Any ideas and thoughts would be welcome. Thanks.

 

[noseall]

Hi, about 15 years ago I moved into an old stone cottage with a concrete extension. There was no insulation, I was working on the whole house so had to stretch my budget and only put int 25mm insulation backed plasterboard on all the external walls and ceilings, along with some loft insulation where I could get it.

Clearly this is not as much insulation as would be ideal. I'm now looking to add more. My initial thought is to get 75mm kingspan style boards add on top of the current boards and then add plasterboard.

There will be a few areas by windows, doors and the large fireplace where this is not possible. Is there a way of figuring out how effective the insulation will be when considering the cold bridges left in areas by the windows? I would hate to put in all the work and effort, reduce the size of the rooms and then find it's not really any better.

Techniques for attaching kingspan to insulated plasterboard walls and then plasterboard on top?

Any ideas and thoughts would be welcome. Thanks.

Foam fix?

 

[Conor]

Thanks noseall

I've not used that before, does it work ok for ceilings? I imagine a good number of support batons needed to hole sheets in place for a while.

 

[noseall]

does it work ok for ceilings?

Why, when you have ceiling joists to fix to?

 

[Ivor Windybottom]

Definitely don't even think about gluing plasterboard to your ceiling!

I'd use insulated plasterboard for the ceiling at least, you'll save half the fitting time although they can get quite heavy.

Find the joists. You could use a stud finder or a neodynium magnet - you're searching for the nails or screws into it, to give away its location. Slide the magnet around until it sticks, put an X on the spot and move on. You'll see rows of X's where the joists are. Find the best straight line that crosses through them with a straight edge, mark it. Put bits of tape down the walls at their ends, just as a guide for later, not necessary but reassuring. Then get long plasterboard screws, long enough for your new insulated plasterboard, plus the old plasterboard, plus about 50mm into the wood. Pre-mark your new boards, based on the measured distance from where its edge will be to your lines. Buy the cheapest possible No Nonsense or similar glue (in a tube). Chop off the nozzle as widely as it goes, put a thick bead on the back of each joist line on your new boards. Put a few blobs on the area between too. Hold the boards up against the ceiling, hold or prop and screw it up. Let the screws do the squeezing, don't push it up beyond or you'll over-squash the glue so it's not supporting it. The purpose of the glue isn't to hold it up, it's to bed between the new and old boards and fill any voids (i.e. high spots in the old ceiling) to ensure there's no movement between them, especially while they're being skimmed later.