Loft joists

This is in a house I'm buying, so no rush, but I would appreciate any informed (!) opinions. It's a Victorian house, so some aspects are not quite up to current spec, and there will be a lot to be done (so beware of many posts in the future!). There are two separate roof voids, neither of which is very easily accessible, although my surveyor has managed to get photos of both. Two things are clear. First, there is very little insulation and second, that the joists look extremely flimsy (3 x 2 at a guess), so to get up there and insulate seems to be a bit hazardous without some forethought. Does anyone have experience with this? Clearly, the best thing would be to tear the ceilings down and start again but that seems rather extreme for a bit of insulation. One approach that came to mind was to reinforce ('sister') the joists to make them more substantial by screwing more timber along the tops. In view of the restricted access, it wouldn't be possible to do this with complete lengths, so each 'sister' would be a number of runs, which might compromise the benefit somewhat. Even if this worked, I would be concerned about wrecking the ceilings while doing it, so is it necessary/sensible to support the ceiling from below (I'm thinking Acros and plywood) to help matters along? Clearly an alternative would be to get insulation blown into the spaces, but in one case there's a bit of brickwork on a chimney breast that could do with sorting and I'm also mindful of the possible need to deal with wiring, roof timbers etc etc. Any thoughts, chaps?

Reply to
GMM
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You need to see just how the roof is built. It's unlikely those 3x2 span the whole distance without support. And, of course, they've been ok for a hundred years or more.

Reply to
Dave Plowman (News)

Modern would 4 x 2. 3 x 2 is a bit small but I'd say my parents

1930's semi was about 3 x 2 that had relatively heavy lath and plaster ceilings not a bit of plasterboard...

Rather than adding new joists in parallel with the existing it would be more usual to cross lay. Easier to fix and makes the whole more ridged.

Reply to
Dave Liquorice

In article , GMM scribeth thus

Parents old house had joists that size and not a problem, even with my

120 KG up there so most of the population should be able to insulate in safety!...

Yes it does!..

Ummm ... total overkill unless the ceilings themselves are in very poor shape i.e. plaster blown or hanging loose..

Well if the wiring needs updating can't see that being a problem in itself. Did your surveyor say anything about that?..

Reply to
tony sayer

Our 1930's dormer bungalow has 3x2 rafters and is standing up OK, even with a bedroom in the roof space on top of the rafters. About 10 to 15 years ago the previous owner replaced all the internal ground floor lath & plaster walls with plasterboard on substantial studwork which I expect are now providing more support than in the past.

Reply to
Mike Clarke

Wow...I didn't expect such rapid responses - Thanks people!

So to summarise so far, it sounds like I may be a bit over cautious in my thinking here....which is probably better than the reverse, as making that error could be good business for a plasterer! I get the sense that lath and plaster in good condition may be a bit more solid than plasterboard, so adding to the structure..though how good the condition is will remain to be seen.....

I'm hoping Dave Plowman's view that things that have stood for 150 years should be fine is right, although I have the nagging concern that the opposite could be true, and things are ready to fall down as I soon as I get to grips with the place.....

Reply to
GMM

why would it be hazardous? 3x2 is standard in victorian lofts.

Sounds like you're inventing problems that dont exist, and failing to find out if they exist before moving on to imagined solutions. The result is less than sane.

Perhaps its time to stop imagining and get some facts. Or pay someone else to insulate it if youre that panicky.

NT

Reply to
NT

Of course I was assuming what's there is still in good condition. Rotten wood is rotten wood regardless of size...

If you do have much in the way of original lath and plaster, be careful with it. Mine was mostly replaced with plasterboard before I bought this place. And the previous owner didn't spend a penny where a halfpenny would do.

Reply to
Dave Plowman (News)

If the joists are in sound condition [1] 3x2 will be fine for crawling over to lay insulation - but not to store heavy items in the attic unless directly over load-bearing walls.

If you're worried, provide a bit more support with a plank under the ceiling across the middle of the span, supported by a couple of props. [The props which Lidl will have for a tenner each next week will be fine, rather than using Acros]

[1] I assume you *have* checked for woodworm, dry and wet rot, etc.?
Reply to
Roger Mills

I would not be partciularly worried - it will take your weight and that of the insulation. I would stick cheap iso/rockwool between the existing joists, then a few inches of rigid PIR foam board insulation over the top. A thin layer of ply (6 or 9mm) if you want to protect the insulation boards from scuffing, and make it safe to walk over.

Reply to
John Rumm

It depends upon the spans and whether they are somehow supported. I have to access a few lofts for my job, and normally 3"x2"s should be OK if spanning a few metres to an internal load-bearing wall. Not good enough to construct a floor on, but OK to stand on. OTOH, the ceiling joists in my mother's Victorian villa/townhouse [thread bleed :)] span from front to back walls and are (or rather, were) only supported by hangers from the purlins. They are visibly sagging and not safe enough to stand on.

Reply to
Hugo Nebula

Thanks for the Lidl tip! Your point [1] is in line with Dave P's advice and yes, the structural engineer and the timber and damp man both say there's not rot up there, which was one of the few positives in their reports (!)

Reply to
GMM

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Sounds like a good plan, John. Hopefully I'll find a way to get good enough access to get some boards up there once I get the place: My surveyor couldn't even find the way (although the structural engineer and timber man both managed....)

Reply to
GMM

Well, on closer inspection of the photos, these span 3m to a central timber (but no supporting wall under it), so I'm hoping that will give them some strength. Perhaps it's not as dodgy as it looks, but we'll find out in due course (cue foot through a ceiling!)

Reply to
GMM

I'd expect the opposite. A well built plasterboard wall with plenty of vertical 3x2's and a horizontal rail along the top and bottom should provide substantial support. I wouldn't be too sure about the support provided by an old lath and plaster wall.

Reply to
Mike Clarke

then you can safely stand a whole family on them

NT

Reply to
NT

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