Raising joist height to accommodate deeper loft insulation material.

[mart]

As my house is very cold shortly after turning the heating off, (and freezing if the heating has not been on). I am considering accepting the extra loft insulation that is currently being offered by various companies. I believe I only have 100mm/4” in place. Apparently (so I was told today) the recommended thickness is now 10”.

The thing is, I boarded the loft floor area years ago, (not fastened down though), and the height of the floor joists would need raising if I wanted to put the boards back down again over 10” of insulation. Apparently, compressing the material down is not a good idea as it would not function in the way intended. Presumably because air (which is an insulator) would be pressed out.

I don’t fancy fastening a load of timber on top of all the joists. The guy today said Wicks sell something called stilts or “raises”. Anyone used these for the same job? Any other suggestions?

 

[BrenM]

I have used them,easy to use and do the job. Cheapest I found was Toolstation.

 

[Kent]

Warm board between rafters with Kingspan or similar and back that up with "Tri-iso" I might not have the spelling right on that, its a thermal blanket with a better u value than the kingspan type products (as long as its correctly fitted) but works best in conjunction with it.

Doing this will make the roof better insulated than anything else in the house.

I suppose you could put tri-iso down onto the loft floor? its very thin and BTW nail or staple it as its a nightmare to screw down as the fibres wrap the screws and break the shank

 

[colnerov]

Hi, you presumably have 6" joists at the moment. So put another 2" on top your 4", then fix 4"x2" at right angles plus noggins as well if you want and fill that with another 4" and boards on top. The boards are helping because they help trap air. Or you could put the other 2" with the 4" and boards back and put another 4" between rafters.

Colin

 

[julianf]

Those raising things are fairly common place. They cost more than i think they should though. (irrelevant to us, however, as all our timbers are quarter rounds, and they wont work with them)

A while back, there was some govt scheme or other where you could get your loft done for free (as in somone else paid for it) if the insulation was under a certain thickness.

Standard / correct (whatever you want to call it), IIRC, is not 10" but 12" (well, 300mm)

 

[Bede]

I had free cavity wall and loft insulation courtesy of British Gas a few months back. I've partially boarded my loft using Loft Legs. Pretty straightforward but my loft bearers all vary so had to improvise in parts by cutting differing sized wooden legs to suit.

 

[rtbcomp]

Those are like the supports we used for the false floor in computer rooms.

 

[hareng]

I turned them down about 5 years ago, loft is boarded up.
Is there going to be any gain the mdf board in its own right keeps the heat in. Had think it was 6" down in workshop then floor boarded over, virtually no gain.

 

[W.olly]

So what will you do when they suggest 14inch of insulation?

just put on another jumper lol

are we all getting soft nowadays.

 

[Wendelspanswick]

Definitely the higher level of insulation the better, our old house was a 200 year old cottage which was never completely warm and always damp no matter how much heat we pumped in.
With our new house, which we built ourselves, we incorporated as much insulation as we possibly could and it's made a huge difference.
It's a large sprawling house as it home for two households (my inlaws live in a large ground floor extension on the side) and its completely heated by a Stanley wood fired range in the main kitchen with pumped central heating to most of the house which also provides ample hot water for showers and baths etc.
We also have a wood burner in our living room which provides space heating only and a 4KW solar array to supplement an electric shower and the underfloor electric heating in the other kitchen.
Fuel costs for the wood burners are zero and we have low electricity bills.
It's simple logic really, the better you insulate your house the less money you have to spend heating it.

 

[colnerov]

Cavity wall guys are trying to persuade my current landlord to let them do cavity wall insulation...personally don't see the point with thermalites.....

Hi, I live in a semi det bungalow built in the late 50s. I had an almost stand up row last year with two young lads on the doorstep trying to get me to have it. I tried to explain that one of the main reasons for cavity walls was to stop damp in the house by the physical barrier of no connection between the two walls, even the wall ties are supposed to run down to the outside. When a new house is built it's installed as the walls go up but leaving a gap between it and the outer wall, they want to blow it in and fill the gap up. I think its a free government scheme, they couldn't understand why I didn't want it done. They are not getting my tax pounds from the government, because I don't think they are giving the government any sort of discount. And I don't want damp in the house. Anyway heat rises so do the roof first.

Colin

 

[rtbcomp]

There's been quite a few cases where cavity wall insulation has had to be removed because it allowed damp to penetrate the walls. Personally I wouldn't have it.

A friend of mine installed it in the internal stud walls of a brand new (1968) house - not for heat insulation, but it improved the sound insulation between rooms and made the whole house feel more solid.

I'm looking for a mid-terraced back-to-back house with pensioners on all sides, they tend to keep their rooms warmer than average (if they can afford to) so the heat will come from their houses into mine!

 

[Cobbler]

We used to live in a 17 century cottage, one evening a young lad knocked at the door, "I'm doing a special deal on cavity wall insulation" I invited him in & said ok when can you do it, He then asked me don't you want to know how much? I said not interested how much, sounds just the job, tell me where to sign. He then started to look a bit flustered realising there was a bit of a wind up going on. I then said if you can get it in, I'll pay, the lad then looked really confused, so I said "how old do you think this house is" 200 years ish, I then told him no house before about 1930ish had cavities, haven't you been told this. He then said "no wonder no-one on this road is interested" He had good training didn't he.

 

[brightspark]

the neighbour over the road from us got conned he payed to get it done . it was double brick all rite but the cavity was only 1 inch max wide and he still went ahead and got it done

 

[normspanners]

There are a lot of solid wall houses around here having external insulation and then re rendered, the sister in law had it done and it has made a big difference the house is warmer and quieter, i am not convinced about the long term strength though.

 

[mart]

I wish my house was like that Fuzzy. I’d sooner have a fan running in the summer than all the heating when it’s cold. You mention Rockwool, I think that is what I used years ago. I’m guessing there is an alternative now that the industry feel is more efficient. However, there was nothing wrong with the efficiency of the insulation in your old home.

 

[Highway_Star]

We've had them knocking here recently, similar tale. The street went up from 1850-1900. All the exterior walls are stone and the interior dividing walls are single brick. (That causes issues in itself. The brick vs stone move at different rates and wall ties weren't invented back then ).

But we do have a loft space above the 1920's brick kitchen extension that could really benefit from enhancing.