How do I plasterboard and insulate my conservatory roof..?

[jon-]

Following on from another thread I'm going to try and change a stty conservatory into a office for 12 months, until I can afford to extend.

As it's double glazed, most of the heat will be disappearing through the roof, which currently looks like this:



The main beams are very strong, I'm not sure about the cross beams.

I'm trying to do this on a budget so plan A will be to plasterboard with loft insulation above, or thermal plasterboard screwed to the cross beams (perhaps adding a few more in). Maybe silver tape the outside.

It doesn't need to look too pretty, and I'm not fussed about losing the light.

Is there much of a weight difference between plasterboard and thermal boarding? Will loft insulation be an effective and lighter replacement?

[jon-]

gazzarose said:

What about using some board type insulation, celotex or kingspan, cut around the beams and stuck up with glue of some kind. 4 inches of kingspan is pretty close to 8 inches of normal rockwool. It'll be alot better than plater board and a couple of inches of rockwool. And would probably be reasonably easy to put back to standard after.

Great idea, but how heavy are these boards? You couldn't stick directly to the plastic, but I like the idea of using boarding where possible for simplicity.

I guess I'd need to vent it too, that shouldn't be a problem though, just cut into one of the side panels.

[jon-]

gazzarose said:

They don't weigh much. They sell it in wickes and bandq. Is basically more efficient begin of polystyrene board.comes in various thicknesses. Not cheap of your doing an entire building but for what you need won't be much I'm it between them and plasterboard/rockwool. Where I've used it on my extension roof. I cut it between the roof joists, probably 16"x 36", and after supporting temporally with bits of wood, I squirted expanding foam in the gap around the board and after its set it stays up fine. Weight wide you could easily carry a few balanced on your head.

Rosscow said:

Simple really, if the main beams are that strong then I'd suggest cutting and fitting some new cross beams so that they finish flush with the main beams (space them to suit plasterboard sheet size).
Then I'd cut celotex so it was a tight push-fit size (in other words, push it in and it won't fall out).
Then screw plasterboard to the underside of the beams.
As it's only temporary I'd suggest some 9mm tapered edge boards, then tape and joint it.
You should be able to get the new beams in, celotex cut and the plasterboard fixed in a day

Thanks guys, looks like I have a plan Not sure about the day part, I'll be happy if I cut the celotex to the right size and stuck it on at the end of day 1!

barryrs said:

Do you have a window that overlooks it?

You dont want it to look crap from above if its your bedroom window so it might be worth covering the underside of the polycarb with something like a black plasti kote spray?

The master bedroom window overlooks it, but the bed is under the window so you can't really look out. A black spray does sound smart, but I presume will also attract a little more heat which is something I need to avoid on sunny days, even with the insulation layer!

[jon-]

Jonboy_t said:

Would it be worthwhile removing the plastic completely, replacing with marine ply and felting it? Might help cut down a bit on the sound when it rains and it would also make lining and boarding a bit easier I would have thought (more solid base to secure to)?

It would be worth it if it was free I like a little rain noise anyway!

[jon-]

Update, the roof now looks like this:



Now I need to work out how to plug the gaps where the cross beams are. I tried expanding foam and it just fell all over my face and floor and clothes and eyes constantly.

And made me very angry.

I now have expanding foam all over the floor.

Help.

[jon-]

Spare tyre said:

could you tape the joints up, then inject the expanding foam

or some variant of the above

Simple yet effective. I like the way you think!

[jon-]

edc said:

For a 12 month period is the additional cost that much less than any increase in utilities cost? Why not just crank up the heating when needed?

I don't know, probably not, but it gets VERY cold in the winter and as I work from home, I'd rather a nice feeling room than freezing my ass off with an electric heater under the desk.

[jon-]

Every issue. The celotex didn't stay in place, I couldn't mount the plasterboard, and even if it had gone to plan i would have still been freezing in winter and boiling in summer. Basically I fked up and gave up.

It's now my covid gym.

Also, wow, thread bump from the past.