Insulating and plastering a new shed

[eastender3]

Hello folks,

Just finishing a new shed being built by builders but I'm a bit confused as to what materials they would use in walls for insulation and ceiling. As it is the walls and ceiling does not look nice, with concrete showing and the ceiling is unsightly.

At the moment, we're undecided if we're to proceed with insulation, as the cost will increase.

What does wall insulation involve?

The builder says, that involves adding plasterboards and then plastering on top?

With the ceiling, not sure what fibre he mentioned and then plasterboards and then plaster?

He is asking £1,500 to the insulation for walls and ceiling for 20 Sq M.

Floor is insulated by them already.

Apart from insulating and costs involved, is there anything else we could apply on the wall, apart from off course masonry paint and in the ceiling. It's not going to be an office or anyone living there, Mrs just wants nice looking finish.

I attach some photos.

 

[stevethespreader]

Why would you want to insulate a shed if thats all it is?

 

[Doggit]

Is 20Sqm the floor area, or the wall and ceiling area. You need to check exactly what he's proposing to do; he may only be offering to put 25mm of celotex on the walls, and maybe 50mm on the ceiling between the roof joists. Depending on what the shed is being used for, holes may need to go in the facias to allow an airflow across the roof above the insulation.

How much space are you prepared to lose in the shed; if he's going to batten the walls to leave a 25mm airgap, then put 25mm celotex, but the time you've added the plasterboard and skimmed it, you've lost almost 6" across the width. As long as the shed isn't going to suffer any water ingress, then call a couple of plasterers in, and get the to quote to dot and dab the walls and plasterboard the ceiling, and then to skim everything.

 

[eastender3]

Is 20Sqm the floor area, or the wall and ceiling area. You need to check exactly what he's proposing to do; he may only be offering to put 25mm of celotex on the walls, and maybe 50mm on the ceiling between the roof joists. Depending on what the shed is being used for, holes may need to go in the facias to allow an airflow across the roof above the insulation.

How much space are you prepared to lose in the shed; if he's going to batten the walls to leave a 25mm airgap, then put 25mm celotex, but the time you've added the plasterboard and skimmed it, you've lost almost 6" across the width. As long as the shed isn't going to suffer any water ingress, then call a couple of plasterers in, and get the to quote to dot and dab the walls and plasterboard the ceiling, and then to skim everything.

Thanks for your detailed reply Doggit.

20 sqm is the floor area. What the builder is proposing is just an insulation board (I think Celotex)and then plaster the walls. On the ceiling, don't know how thick the board he is going to use and then plaster over it.
The airflow across the roof, he did not mention this and don't think he is going to do it or even does not know, it needs doing?

No one is going to live or use as an office in the shed. It'll be used to sit down during the summer months and a chest freezer will be placed there.

We're told that's best to insulate due to dampness and other risks, not sure if he said this to get more work and off course more costs.

We're conscious that we would lose space. However, our only concern at the moment is that we don't want to see the bare concrete walls and timber roof joints. Is there anything we could do to make the walls and the ceiling nicer to look at? Or is the insulation the only option?

 

[Doggit]

If you're going to put a chest freezer in there, then either it needs to be able to handle cold temperatures, or the shed needs to be insulated. How airtight is the shed going to be; does it have a uPVC door, or just a couple of wooden doors. I reckon you can get away with any airflow across the top of the roof insulation, as there' no real moisture to then rot the plywood roof.

I'd be inclined to say that if you can find a freezer that will handle low temperatures, then just dot and dab the walls with plasterboard.

 

[eastender3]

If you're going to put a chest freezer in there, then either it needs to be able to handle cold temperatures, or the shed needs to be insulated. How airtight is the shed going to be; does it have a uPVC door, or just a couple of wooden doors. I reckon you can get away with any airflow across the top of the roof insulation, as there' no real moisture to then rot the plywood roof.

I'd be inclined to say that if you can find a freezer that will handle low temperatures, then just dot and dab the walls with plasterboard.

Hello and thanks for your reply.

Yes, it has uPVC door and also uPVC two windows at the sides. We had a chest freezer before in the old shed with no problems.

Is there no alternative to insulation the walls and ceiling? Can we just plaster the walls and put wooden cladding in the ceiling?

We are conscious we'll lose space in the walls and the cost increase.

If there is no alternative apart from applying masonry paint on the inner walls and don't know about the ceiling, how much do you think it'll cost to do the basic insulation?

The builder is asking £1.5k, is that reasonable?

 

[Doggit]

If you're fine with the freezer in a cold room, then you don't need to insulate place. You can just plaster the walls and then paint them, or you can dot and dab the walls with plasterboard and plasterboard adhesive; the plaster's would also put plasterboard on the ceiling, and they'd then plaster the whole lot. You can ask the builders to quote just for this, and you can call a couple of other plaster's in for competitive quotes.

It's difficult to judge the builders quote, without knowing exactly what they are offering.

 

[eastender3]

If you're fine with the freezer in a cold room, then you don't need to insulate place. You can just plaster the walls and then paint them, or you can dot and dab the walls with plasterboard and plasterboard adhesive; the plaster's would also put plasterboard on the ceiling, and they'd then plaster the whole lot. You can ask the builders to quote just for this, and you can call a couple of other plaster's in for competitive quotes.

It's difficult to judge the builders quote, without knowing exactly what they are offering.

Thanks for the reply.

We wanted to just plaster the walls and paint them, but the builder advised against this and says large cracks would appear on the walls? He said without adding plasterboard on the walls, it's not a good idea to just plaster on the inner walls. Is this true?

On the ceiling is there no alternative to adding plasterboard and then plastering?.

If there is no alternative, we could just plaster the walls and then paint and add plasterboard on the ceiling and then plaster and paint.

Thanks

 

[Doggit]

Putting plasterboard on the walls first, will give a much flatter surface, and dry quicker, so it's a good way to go, but not essential. Everything shifts and settles a bit after it's built, so you'd possibly get a few small cracks, but not enough to justify needing to put up plasterboard. But putting the plasterboard up will make the room a little warmer.

You could plasterboard the ceiling, fill the joints, and then paint. You could use plywood, if you don't mind the inevitable gaps at the joints - it's totally down to you.

As always, go and get alternative quotes, and if you're not happy, leave it for a bit.

 

[catlad]

I have seen problems with dot & dab on external single skins so thats maybe another reason he wants to use insulation.

 

[eastender3]

Now I've agreed to do insulation. He is going to use thermal boards then plaster on inner walls and ceiling. On the ceiling he is going to use insulation wool and then thermal boards and then paint.