Kitchen/shed extension

rigby44

Hi all,

Recently moved into a house, 1930’s with solid walls. The kitchen has been extended (on the cheap I think) into what used to be a shed. It seems the insulation is slim to none as its always freezing, condensation on the walls and black mould when you move the kickboards. Put a dehumidifier in there, showing 80-90% RH and wont go below 70% even with the thing running for hours. Goes straight back up once the dehu goes off.

Any advice would be great.

Thanks

Ian

Jeepers_Creepers

Dot and dab insulated p'board to the walls, and ceilings too if there's no way to insulate above it.

What are the walls made from? A single-skin block? Possibly worth, then, tanking the insides before D&Ding the boards in case there's any 'penetrating'. What's the floor made of? Any way to add even a thin layer of insulation on there?

Whatever thickness of insulated board you add to the walls will transform the place. If you are really pushed for internal space, then just a 2" layer will give excellent results.

rigby44

Jeepers_Creepers said:

Dot and dab insulated p'board to the walls, and ceilings too if there's no way to insulate above it.

What are the walls made from? A single-skin block? Possibly worth, then, tanking the insides before D&Ding the boards in case there's any 'penetrating'. What's the floor made of? Any way to add even a thin layer of insulation on there?

Whatever thickness of insulated board you add to the walls will transform the place. If you are really pushed for internal space, then just a 2" layer will give excellent results.

Many thanks for your help!

Apologies for my naivety, do you mean applying something like the product below to the internal walls?

Seems I cant provide links yet, but its Knauf Wallboard.

Jeepers_Creepers

rigby44 said:

Many thanks for your help!

Apologies for my naivety, do you mean applying something like the product below to the internal walls?

Seems I cant provide links yet, but its Knauf Wallboard.

Yes, Knauf amongst others make it - it's plasterboard but with a layer of high-quality polyurethane insulation bonded to it so it can be fitted in one go. Eg: https://www.insulationsuperstore.co.uk/product/celotex-52-5mm-insulated-plasterboard-pl4040.html

Whatever thickness you add - it's starts at around 35mm overall, so 25mm insulation - will make a huge difference, but if you can go for thicker - the size above is probably the best compromise between insulation value and not losing internal space.

The room I'm sitting in now was the attached single-skin garage. I laid a DPM on the floor (just in case there wasn't one already under the concrete there), bringing that up a good couple of feet up the external walls, battened these walls at 600mm spacing using treated roofing battens (2x1), infilled the space between with 1" Jablite (cheap expanded-polystyrene insulation) and then overboarded using the 35mm insulated p'board. Jablite also on the floor, and T&G floorboards on top. Celotex in the celing. The room is now warm enough with just being heated by the old Plasma TV I use as my monitor - 250W? (The room is only 8' wide, so I was conscious of losing too much width - which is why I kept it to a min.)

(The next time I do a similar job, I'd first tank the wall insides (tobesuretobesure) and simply D&D the 65mm insulated boards straight on - quicker, easier, and more effective. If you are fitting, say, kitchen units on the wall, you'll be screwing right through in to the actual wall behind. This will also act as extra anchors for the D&D boards - in theory the foam could melt in a fire and cause the boards to fall off. If you are not going to be doing this, then the boards should also be fixed through mechanically using a suitable fixing - I think they make non-metal ones so's they don't act as cold bridges.)

What's your floor made of?

Can you get above the ceiling to add insulation there?

Doozergirl

Knauf Wallboard appears to be a standard plasterboard.  Insulating plasterboard has a layer of solid insulation attached to the back of it.  Varying thicknesses are available.  Don't use the polystyrene backed one, it isn't as insulating. 

You need more insulation on the ceilings, so you'd use solid insulation between the joists (leaving an air gap over the top) and then a layer of insulated plasterboard over the joists.  

A correctly sized radiator when you've finished.  

You need to keep the ground level outside the building lower than floor level and make sure you have trickle vents in the windows and a decent extractor for cooking.  That will help reduce damp/humidity but you'll be fighting a losing battle until you insulate properly.  You currently have a cold room and you're producing lots of moisture - condensation central!  

FreeBear

Any wall units in the kitchen ?

If so, you'll need to think about structural support for them. Screwed to plasterboard won't work for more than a few minutes, so Celotex/Kingspan insulation topped off with a sheet of good quality plywood may be in order.

An extractor over the hob/cooker will also help to keep moisture levels under control.

Jeepers_Creepers

FreeBear said:

Any wall units in the kitchen ?

If so, you'll need to think about structural support for them. Screwed to plasterboard won't work for more than a few minutes, so Celotex/Kingspan insulation topped off with a sheet of good quality plywood may be in order.

5" screws... :-)   

FreeBear

Jeepers_Creepers said:

FreeBear said:

Any wall units in the kitchen ?

If so, you'll need to think about structural support for them. Screwed to plasterboard won't work for more than a few minutes, so Celotex/Kingspan insulation topped off with a sheet of good quality plywood may be in order.

5" screws... :-)   

IF you are real lucky and screw in to the timbers first time and the timbers are in the right location... Even then, you'd still need to account for the shear loading on the screws.

Jeepers_Creepers

FreeBear said:

Jeepers_Creepers said:

FreeBear said:

Any wall units in the kitchen ?

If so, you'll need to think about structural support for them. Screwed to plasterboard won't work for more than a few minutes, so Celotex/Kingspan insulation topped off with a sheet of good quality plywood may be in order.

5" screws... :-)   

IF you are real lucky and screw in to the timbers first time and the timbers are in the right location... Even then, you'd still need to account for the shear loading on the screws.

I was thinking in terms of 65mm insulated board D&D'd to the walls. The 5" screws would go right through to the blocks behind.

Yes, they'll form thermal bridges, but hopefully this won't be an issue as the heads will be set behind the units. For wall units, use continuous rail, and not individual brackets.

An idea that isn't daft - once you know the rails are going to be level and the correct size, give the back contact area of them a smear of adhesive - doesn't matter too much what type (eg Poly Gorilla Glue or Stixall etc). Screw down firmly - and potential shear taken care of.

grumbler

Jeepers_Creepers said:

...with a layer of high-quality polyurethane insulation bonded to it

I'm sorry to be pedantic, but polyurethane foam is soft. It's the one used in furniture.

Celotex is polyisocyanurate foam

Jeepers_Creepers

It's ok - I love pedants. Honestly...