Another loft boarding question...

[dingy]

Hello,

We have just had our 270mm of loft insulation installed as part of the free scheme. I want to board out a small section of the loft for storage but am aware that I can't just compress the insulation down. I know there are lots of threads out there about this but I wanted to ask the question in context of my specifics.

I am going to be storing mostly boxes, a couple of which will be as heavy as 30kg. The rest will be nowhere near as heavy as that. The area I want to board is roughly 4 metres by 6 metres, with the loft hatch near enough the middle of that space.

I have seen that loft stilts are an option, but I can't see them stocked widely any more and am not that keen on them (they just don't look sturdy enough!). If I were to ignore that and run new joists perpendicular to the current ones what would be my preferred method for that size area and weight of stored material? And are there any other considerations that I should have, perhaps around access?

 

[andyroo1]

Hey,

I just had my insulation too and boarded the loft today- with the thickness of the insulation i would say unless you intend the loft to be "habitable" i would not use joists as you will end up stacking up 2/3 joists to get to the right height.
The loft stilts are great- i was quite skeptical at first but they are stronger than they look - my attic is quite small so mine was like the below:
View media item 52394Starting on a tall rafter, running to another at the other side with a stilt in the middle for stability and then i did inbetween with pallet slats and it worked perfectly. View media item 52395

 

[dingy]

Great, thanks for that! Where did you get your stilts? One thing I'm not clear on is your end rafters - I don't really have a similar arrangement. I have joists that run across the ceiling and fix into the actual roof rafters. As I don't have a rafter/joist running at each end to fix into like you have can I just use a stilt at the ends to lay he boards on?

That feels like it might not make a lot of sense. Please do ask for clarification if needed!

 

[andyroo1]

Hi,

Yes you can use the loft legs at each end- they are available from b&q and about £1.80 each.

What are the dimensions of your loft though, & do you have a quick sketch to show the layout so i can get some idea.

The stilts are very strong and should be fine but would need some idea of the size to give an accurate opinion.

 

[freddiemercurystwin]

The stilts are not designed for point loading. They are designed to be used en masse at no more than 600 centres. That's why timber joists perpendicular to the existing is so much better, because the loads are transferred far more equally. You can lead a horse to water .....

 

[dingy]

Maybe I should have been clearer! I'm definitely not looking at point loading, I would be using the stilts throughout the area to be boarded at sensible intervals so that weight is distributed evenly. However if raised joists are not that much more expensive and are relatively easy then I'm happy to do that.

(Bad) drawing to follow.

 

[Ecohouseconvertor]

(copy of a post I put in on another tread on the same topic)

Sorry for the late reply – been away on holiday – i guess you’ve already done the job, but for future reference....

There are several options for this type of job:

• You can use extra timber joists like freddymercurystwin rightly says. They are cheap but heavy, and work ok.
• You can use Diall Loft Stilts http://loftstoragestilts.com/ or Wickes (?) Loft Legs like you were planning to do. They hold the boards up but the smaller the boards are, the more you need, and so that can be time-consuming. You also need to check your joists are evenly spaced, otherwise it can be difficult to fit the boards on to the top of the legs/stilts (if the joists are too far apart, the boards may not reach the stilts). Individually, they’re quite cheap, and they are very light. I don’t know how safe they are to walk upon.
• You can use the LoftZone StoreFloor www.loftzone.co.uk, which is faster to install, also lightweight and also forms a very strong deck, ok to walk upon. But it’s not as cheap as the others.
• Or you can go down a different route and use insulated boards, like this one http://www.space-insulation.com/board.html . You would usually need 2 or 3 on top of each other to meet the same U-value as the 270mm of wool quilt. You’re not meant to walk on them.

Another point, I’ve been told that you should leave an air gap between the insulation and the underside of the boards, and allow air to flow between the two. This is to reduce the chance of condensation building up on the underside of the boards, and dripping down below. (There’s a risk the dew point could form there). So if you’re using timber or the stilts/legs, then you’d need to build them up higher than the insulation. The StoreFloor already does this and the insulated boards don’t need them I guess.

How did you get on with your install?

 

[valve90210]

I hate to bring back a long dead thread but having spent a chunk of today messing around in the loft hoping to get an area boarded and failing miserably as the previous owners have had new insulation installed meaning I need to raise the joists in order to clear the insulation.

I have read through several threads on this and seen mentioned many times loft stilts which have on the whole been met with disapproval, most seeming to prefer additional timber joists mounted on the original joists. This had been my initial plan but I was worried that the extra timber would be really heavy and along with the boarding and a load of stuff stored up in the loft might be too much for the joists to support?

Are my fears re the weight unfounded? If so I shall get some timber and get installing...

Any help very much appreciated.

 

[jabuzzard]

There is a third option that I have employed, and is cheaper than LoftZone, possibly cheaper than stilts, and less weight than extra timber. You also loose less height in your loft.

Basically you buy 100mm celotex/kingspan cut it into strips, feed into the loft and just lay over the joists. You can then just cover it with chipboard and secure in a few places with 150mm screws.

It does mean throwing away any insulation above joist level in the area to be boarded, but it is quick, reliable and easy to do.

 

[MobyDick2012]

There is a third option that I have employed, and is cheaper than LoftZone, possibly cheaper than stilts, and less weight than extra timber. You also loose less height in your loft.

Basically you buy 100mm celotex/kingspan cut it into strips, feed into the loft and just lay over the joists. You can then just cover it with chipboard and secure in a few places with 150mm screws.

It does mean throwing away any insulation above joist level in the area to be boarded, but it is quick, reliable and easy to do.

I have checked with Celotex and they say you need to put 12mm ply over joists before the Celotex shett to prevent crushing. then the chipboard sheets over that for the floor. Which makes it quite expensive....

 

[jabuzzard]

I have checked with Celotex and they say you need to put 12mm ply over joists before the Celotex shett to prevent crushing. then the chipboard sheets over that for the floor. Which makes it quite expensive....

They might say that, but if you are using it for "light" storage you don't actually need it. My sisters loft has been down for two years now and it is doing just fine. There is no sign of the crushing that Celotex suggest and the storage is more than just empty boxes.

Now if it where a floor in a living space that would be different. If you are really bothered you could screw a plank of wood over the joists to increase the surface area, the Celotex rests on, but honestly it is not needed.