Loft insulation help + stud walls

lukekelly19

I am going to insulate my loft. Partly this is quite straightforward - put 200mm of insulation above the joists (and the exisitng 70mm insulation). But there are a couple of things I'm not sure about.

1/ It has been suggested that I remove the stud walls. They go around the edge of the loft room, and are insulated. However, the assessor said that it would be a good idea to get rid of the walls a) as they were outside the thermal envelope created by the loft floor/house ceiling insulation b) it would create more space and c) (presumably) the floor the other side of the stud walls could also be insulated. On c), if I kept the stud walls, and only insulated up to them, would the roof still lost a lot of heat? What would be the difference between getting rid of the stud walls and insulating all the way, and not? i.e. how important is it for the whole span of the loft floor to be insulated?

2/Is there an easy way to tell if your loft room needs ventilation tiles/grills? Is there a way to see if the existing roofing membrane is fully vapour permeable?
-How easy/expensive is it to install ventilation tiles/grills?

3/Can I attach loft legs to boarding? Or does it need to be screwed into wood (ie joists)? It would be easier to keep the exisitng boarding and lay new insulation on top!

grumbler

lukekelly19 said:

I am going to insulate my loft. Partly this is quite straightforward - put 200mm of insulation above the joists (and the exisitng 70mm insulation). But there are a couple of things I'm not sure about.

1/ It has been suggested that I remove the stud walls. They go around the edge of the loft room, and are insulated. However, the assessor said that it would be a good idea to get rid of the walls a) as they were outside the thermal envelope created by the loft floor/house ceiling insulation b) it would create more space and c) (presumably) the floor the other side of the stud walls could also be insulated. On c), if I kept the stud walls, and only insulated up to them, would the roof still lost a lot of heat? What would be the difference between getting rid of the stud walls and insulating all the way, and not? i.e. how important is it for the whole span of the loft floor to be insulated?

In fact you insulate the ceiling of the first floor, not the loft room. If you don't insulate the eaves behind the stud walls, part of the ceiling won't be insulated enough.

It doesn't matter how much heat the roof looses. What matters is how much heat gets from the first floor to the loft. If the ceiling is insulated well, very little heat gets to the loft and there is no anything for the roof to lose.  The better you insulate the ceiling/floor, the colder your loft room will be in winter.

2/Is there an easy way to tell if your loft room needs ventilation tiles/grills? Is there a way to see if the existing roofing membrane is fully vapour permeable?
-How easy/expensive is it to install ventilation tiles/grills?

The room needs better ventilation if you see condensation there or things get damp. Normally the loft is ventilated through the eaves. If the eaves are blocked by stud walls or by insulation, then you possibly do need other ways like ventilation tiles. You can add insulation to the eaves (without boarding them) and keep the stud walls, but If the walls block ventilation this can be a problem.

If it's nonwoven membrane (not felt or shiny plastic film) then it's breathing.

3/Can I attach loft legs to boarding? Or does it need to be screwed into wood (ie joists)? It would be easier to keep the exisitng boarding and lay new insulation on top!

AFAIK, legs are designed for joists. If you want to lay boards after adding insulation, I don't see any point in keeping the old boards under the insulation.

lukekelly19

Hi Grumber, thanks so much for your detailed and definite reply! It's very, very helpful.

Looks like I'll have to take down the stud walls : )

FreeBear

lukekelly19 said: Looks like I'll have to take down the stud walls : )

How do you access this loft room - Is it by way of a proper staircase or just a ladder though a hatch ?

If the latter, it is just a glorified store room, so removing the stud walls (assuming they are not structural) & boards and insulate the entire area is the way to go. Use plenty of loft legs, and put the boards back down. If you retain some of the studs, it will give you somewhere to put up shelving.

With a proper staircase, insulate the space between walls & roof, and add loads of insulation to the "ceiling" of the loft room. Don't forget to leave a generous gap between any insulation & tiles (or felt). 50mm at a minimum to allow air to circulate. You'll probably need some ventilation up there to avoid condensation once the roof/walls are insulated.

weeg

Before you do any of that, get someone to check that the walls aren't actually structural! They might form part of roof trusses.

markin

They are very likely to be structural, That man sounds like a danger to others.

grumbler

Well, generally, removing the walls doesn't necessarily mean removing the studs.

weeg

grumbler said:

Well, generally, removing the walls doesn't necessarily mean removing the studs.

You'd be surprised at what some people do to their houses.