Loft insulation depth and use of loft legs

[whatknot]

My daughter has just bought a bungalow which has virtually no loft insulation, what is the current reccomended insulation depth?

Also they are looking to utilise some of the loft space for storage, only a small amount for such as Christmas decoratios/tree etc, the companies selling the likes of Loft Legs of course say they are wonderful but found one installer on youtube saying they were rubbish and distort over time (which I can't quite see how if fitted correctly, screwed to joist and boards to the top)

Just wondered if others have any thoughts on their use as once they fit new insulation they do not want to lose the benefit by compressing it laying boards on it

 

[ChaiLatte]

The recommended depth of insulation is likely more widely published, and thus accessible to a general search:

https://assets.publishing.service.g...factsheet_11.11.16_LOFT_INSULATION_LOCKED.pdf

The loft legs will work so long as they are subject to compression only and you follow installation and loading guidelines (e.g. https://www.loftshop.co.uk/UserFiles/Files/loft-leg-fitting-instructions.pdf).

Think about how you put things into a loft: you push them up through the trap door ahead of your body and then slide them along the boarding thence to gather dust for 25 years until your children slide them back again and skip them after you die.

Hence, in order for the legs to work, you have to provide your own means of resisting the sideways force from the sliding. Having the boards restrained at both ends by gables works in one direction; you have to think about the other way.

If you are only partially-boarding the loft, this restraint is more challenging. Similarly, if you are only partially boarding, a small upstand/stop block at the edge stops items being pushed to far.

 

[whatknot]

The recommended depth of insulation is likely more widely published, and thus accessible to a general search:

https://assets.publishing.service.g...factsheet_11.11.16_LOFT_INSULATION_LOCKED.pdf

The loft legs will work so long as they are subject to compression only and you follow installation and loading guidelines (e.g. https://www.loftshop.co.uk/UserFiles/Files/loft-leg-fitting-instructions.pdf).

Think about how you put things into a loft: you push them up through the trap door ahead of your body and then slide them along the boarding thence to gather dust for 25 years until your children slide them back again and skip them after you die.

Hence, in order for the legs to work, you have to provide your own means of resisting the sideways force from the sliding. Having the boards restrained at both ends by gables works in one direction; you have to think about the other way.

If you are only partially-boarding the loft, this restraint is more challenging. Similarly, if you are only partially boarding, a small upstand/stop block at the edge stops items being pushed to far.

Thanks for your reply, I asked re the depth just to confirm that 11" is the recommended depth, and yes I knew there are numerous web pages on it, just wanted confirmation from users

Re loft legs I was looking more for some user information but take on board what you say re partial boarding and support each end

 

[Sachakins]

If its a trussed roof these are good.
https://www.toolstation.com/loft-le...gJ_GrTEcEQuHv7oX8aYNHXFwG1IpdIpBoCKEsQAvD_BwE

 

[Doug71]

I did similar for a friend last year.

The existing insulation was only 100mm so got some 170mm to go on top then used some loft legs and loft boards to form a platform, bought it all from B&Q and it made a good solid job. At the same time I also fitted a better loft ladder and did a bit of handrailing in the loft, it has made a decent usable storage area.

 

[whatknot]

If its a trussed roof these are good.
https://www.toolstation.com/loft-le...gJ_GrTEcEQuHv7oX8aYNHXFwG1IpdIpBoCKEsQAvD_BwE

Thank you, I did see these but no its an older roof so not usable

 

[whatknot]

I did similar for a friend last year.

The existing insulation was only 100mm so got some 170mm to go on top then used some loft legs and loft boards to form a platform, bought it all from B&Q and it made a good solid job. At the same time I also fitted a better loft ladder and did a bit of handrailing in the loft, it has made a decent usable storage area.

Thank you that sounds promising

This situation has an added problem, in that the boiler is in the loft so will require safe access to it if it remains there, as its about 20 years old and will require replacing soon, so it may be more convenient to move it into the bungalow kitchen which has an extension so room for it

It also needs a loft ladder as there is no fixed access at present, lots of jobs all at once

 

[bp122]

I think the Loft Legs come in 2 heights, 200 and 300mm (I think), depending on how much insulation you are going for. Our insulation is 200mm thick, but it is important to leave an air circulation gap at the top to avoid moisture / mould issues. So, I went for the longer one. I boarded the "gangway" in the loft three years ago, no warping or distortion has occurred. Get the make which says Loft Legs:
https://www.amazon.co.uk/Insulation...&hvtargid=pla-585064336236&psc=1&gad_source=1

There may be knock offs in the market which are sub par?

I used thick torx screws to secure into the joists and spaced them properly (each loft board MUST have contact with at least four - one in each corner)

 

[whatknot]

I think the Loft Legs come in 2 heights, 200 and 300mm (I think), depending on how much insulation you are going for. Our insulation is 200mm thick, but it is important to leave an air circulation gap at the top to avoid moisture / mould issues. So, I went for the longer one. I boarded the "gangway" in the loft three years ago, no warping or distortion has occurred. Get the make which says Loft Legs:
https://www.amazon.co.uk/Insulation...&hvtargid=pla-585064336236&psc=1&gad_source=1

View attachment 195073
There may be knock offs in the market which are sub par?

I used thick torx screws to secure into the joists and spaced them properly (each loft board MUST have contact with at least four - one in each corner)

Thanks for your input, these are one of two types I have been looking at the other is the loftzone storefloor

I am going to do a more thorough measure up tomorrow and then estimate what is required

 

[Doug B]

I’ve boarded quite a few lofts with the new thickness of insulation usually in new builds, I don’t bother with the commercially available legs just simply pre cut some lengths of timber to the height of the insulation plus the thickness of timber & screw these to the ceiling joists.
I then screw lengths of timber to these uprights level with the top & then screw the ends to the rafters.

This gives a really sturdy base for the flooring & also means I can progress from the hatch a joist at a time standing on the previous joist & so only have to move a very small amount of insulation

 

[whatknot]

I’ve boarded quite a few lofts with the new thickness of insulation usually in new builds, I don’t bother with the commercially available legs just simply pre cut some lengths of timber to the height of the insulation plus the thickness of timber & screw these to the ceiling joists.
I then screw lengths of timber to these uprights level with the top & then screw the ends to the rafters.

View attachment 195080

This gives a really sturdy base for the flooring & also means I can progress from the hatch a joist at a time standing on the previous joist & so only have to move a very small amount of insulation

View attachment 195079

I quite like the simplicity of that, I will have a measure up tomorrow and see if thats a possible way round it, are you screwing through the rafter into the upright?

 

[ChaiLatte]

I don’t bother with the commercially available legs...

Do you have any cost information that might help someone choose this alternative?

Pick a square metrage of loft; assume a joist spacing and work out the material and labour cost of the 3" x 2" solution compared to the loft leg solution.

Note that the OP does not have a trussed roof as you show, so it would be good to speak on the implications of that.

Similarly, the economics of one or the other would depend on the boards which you use on top. In your picture, it appears to be T&G chipboard probably 2.4m x 0.6m. If you cannot poke a 2.4m long board through the loft hatch, the cost calculation will be different.

 

[JSW]

Isn't there a weight implication also?

 

[XTiffy]

When the Building regs. needed 250mm deep loft insulation in my then newbuild, the ceiling joists were 150mm so I laid 150mm insulation between. I then added 100mm x 50mm timber across the whole area spaced to suit insulation width. This meant I had a solid structure to lay chipboard floor, with 250mm insulation in place. I have never been keen on loft legs but as always it depends what you want to store or access.

 

[Ross Buchanan]

We re-insulated a loft for a customer, with a new ladder and a storage area around the hatchway. Despite my scepticism, the customer insisted we used some loft leg things from B&Q as he'd already bought them. Except he'd bought one box and we needed 5. Also, due to poor access we had to use those little 4'x16" boards.
The existing joists were unevenly spaced, which did not coincide with the junior sized floorboards. I extended the sides of the loft hatch so there wasn't a gap with dusty knauf showing, and screwing the floor boards to that stiffened it all up ok. All screwed together, it seemed reasonably sturdy- ok for Christmas deckies and empty suitcases, not really good for boxes of books or LPs.
All in all, it seemed an expensive ballache to solve a problem badly, when there's quicker, cheaper, easier, better, sturdier solutions available

 

[codaamok]

We used the LoftZone Storefloor system and they installed it for us.

I paid £1875 which included the floorboards system and chipboard, an additional 100mm insulation (taking me up to 200mm), a ladder, hatch enlargement, covering nearly 19m2. This included a 25% discount for doing the order as I dithered for a while, and they said it's a promotion they do every year in the summer. I had it installed at the start of July.

I have a hot water extension tank in the loft, so they boarded around that.

There is a weight limit per m2, approx 25kg IIRC, so keeping under that you'll be fine avoiding issues like sagging chipboard (I guess go for OSB boards, that's what a lot of people use on YouTube). Just be realistic with what they want to put in the loft, as the weight you put on any support system will include the joists, too, and I've read some stories of people seeing their ceilings dipping after lugging heavy audio equipment in their lofts.

Also, if you do DIY it, keep clearance around the eaves and do not let insulation touch the underside of the boards you lay down (or at least don't compress it) otherwise this will create a moisture problem.

I hope this helps.

 

[Ross Buchanan]

25kg/M2 seems reasonable, but an adult walking or crawling across that floor is 3 times that

 

[codaamok]

25kg/M2 seems reasonable, but an adult walking or crawling across that floor is 3 times that

Yes. I don't recommend storing bodies up there.

 

[whatknot]

We re-insulated a loft for a customer, with a new ladder and a storage area around the hatchway. Despite my scepticism, the customer insisted we used some loft leg things from B&Q as he'd already bought them. Except he'd bought one box and we needed 5. Also, due to poor access we had to use those little 4'x16" boards.
The existing joists were unevenly spaced, which did not coincide with the junior sized floorboards. I extended the sides of the loft hatch so there wasn't a gap with dusty knauf showing, and screwing the floor boards to that stiffened it all up ok. All screwed together, it seemed reasonably sturdy- ok for Christmas deckies and empty suitcases, not really good for boxes of books or LPs.
All in all, it seemed an expensive ballache to solve a problem badly, when there's quicker, cheaper, easier, better, sturdier solutions available

What are those quicker easier cheaper options?

 

[whatknot]

Well I had a measure up this afternoon, the rafters are a mere 75mm deep x 50mm wide

Spacing between them is random, from 36cm to 48cm

On the good side there are two sturdy brick wall either side of the hall and other brick wall where it needs a walkway to the boiler access point

Plenty of loose boards up there, 14 x 1220mm x 325mm and three 2.4m x 600mm (there is a decent sized hatch)

So may forget the loft leg plan and use timber instead

There is approximately half the floor covered in what is now 75 to 100mm insulation, its a bit random some here, some there so its hard to be precise how much is there

The questions being does it require the whole lot redoing? or can the old insulation be used?

To bring it up to 270mm depth, does it require any form of retention, other than the parts that require the walkway access and some storage space both of which will be over brick wall supported rafters