Internal rigid insulation board- which is the best product?

Question

I have a small area of ceiling in a chalet-style house that backs directly onto the rafters. I have removed the polstyrene tiles to reveal (plaster?)boarding - which I will artex. Is there a board I can fix over the mess to increase the level of insulation before artexing? Two 8x4 sheets would cover the area - where can I get this quantity cost-effectively?

Thanks

Answer 1

i would recommend a lightweight backer boards and use screws to fasten it on the wall. I would recommend Marmox tile backer boards as the core is XPS and therfore you get high insulation values and it would have also waterproof properties.check www.marmoxboard.com

Answer 2

plasterboard might be  ok, at lesst it would take artex

Answer 3

With the rising price of gas and electricity, more or less whatever you do in the way of insulating is going to be cost effective!

The biggest problem you are going to have is fixing the product to the ceiling.  In theory you could use insulated plasterboard and stick it to the existing ceiling, but there is no guarantee the existing surface is going to take the weight, messy.  This actually applies to simply artexing the mess you report.

You will need to involve the rafters, either remove the existing plasterboard, or use a stud detector and a bradawl locate the rafters.  Removing the plasterboard gives you the advantages of being able to insulate behind the plasterboard and to find or fit noggins along board edges so the board can be fixed along all edges not just to the rafters.

One way or another you know where the rafters are, you may know where the noggins are.  Board edges need to be fixed every 100mm/4" all round and at 150mm/6" intervals along the intermediate rafters.  If you have left the original plasterboard in place you can stick insulated plasterboard to the original ceiling with plasterboard adhesive and hope that this compensates for the absence of fixings along the edges you cannot fix to noggins.  Note the original plasterboard was fixed with nails and it is likely that you will occasionally find one of these when you fix your new board!

Fixings: even plasterers prefer screws to nails, these can be put in with an ordinary drill with a ph2 bit, but for less than a tenner you can get a special bit that stops s******g once the s***w has indented the cartridge paper, the plaster has no strength, so any s***w that sinks through the paper is ineffective.

For most people a 9.5mm sheet of plasterboard is a bit of a struggle at ground level, once it is above your head and you are trying to put screws into it, it is nigh impossible, you will need to have some very strong friends.

A further advantage of stripping back to the rafters is that you can use some pretty thick insulation board, a 75mm plasterboard s***w should hold 9.5mm plasterboard and 40mm of Celotex, or kingspan, unfortunately these boards, light as they are do not hover, whilst you fix the plasterboard!

Good luck!

Answer 4

There are lots of different insulation boards available.  Styrofoam would probably be the cheapest.  Try the local hardware stores, or look in the yellow pages under "insulation".  There is also fiberglass board, mineral wool board and other insulation materials, but they are a lot more expensive than styrofoam.

Answer 5

Kingspan insulation is what you need, the only downside is its about 45mm thick but would certainly more than do the job.