Loft Storage floor

[Clint Sharp]

Hi I've just had my loft insulated to 270mm and now have a problem, where the hell to put all the boxes that came out of it without crushing the insulation or wrecking the insulation every time I need a box out.

My loft has what I believe is called a purlin beam running around the loft. The bottom of this purlin is a couple of inches above the top of the insulation so I'm wondering if I can attach some joist hangers to hang some 4x2 joists across the span (2.8mtrs) then lay chipboard loft flooring over them? It should be possible to support the 4x2 in the middle of the span if necessary but it's not going to be supporting a huge amount of weight and I'd rather not if possible. It's not going to be used to walk on, only be crawled on to retrieve/replace boxes, there's no possibility of it ever being walked on as the loft is only

5ft and will be around 4ft after this.

Does this sound a reasonable plan?

[jgharston]

Additional 3" or 4" joists on top of and perpendicular to the existing floor/ceiling joists and panel over that?

JGH

[Clint Sharp]

Alas the insulation is laid in two layers perpendicular to each other so to do that would mean having to lift all the insulation and re-lay it, not impossible but I dislike working in the loft and with raw mineral wool especially so a 'floating' storage floor would be my preference if it's at all possible

Adding only an extra 4" height to the existing loft 'floor' would crush down the insulation too.

[Skipweasel]

That's what I did and it's worked fine.

[Skipweasel]

Nah, just tear it where the new joists are going.

[stuart noble]

A breeze block at either end, and a couple of lengths of 2" x 1" between them? Not much deflection unless your boxes are really heavy

[Clint Sharp]

In message , Skipweasel writes

OK but what about the crushing of the insulation? It's going to halve the depth if I do that and surely that's going to stop it working so well?

[Tim Watts]

Clint Sharp ( [e-mail]) wibbled on Saturday 29 January 2011

12:02:

Hmm. Sadly this would have been easier to solve before the new insulation went in.

But - change the suggestion for 4" joists to 6". You'll crush down the insulation by one inch which will make no practical difference.

You say the new insulation is 90deg to the old. So the old was 4" bewteen the ceiling joists and the new is 7" crossways giving you 11" or 270mm

*total*?

In which case, perpendicular joists would be fine.

You will get away with 500mm spacing easily, and even 600mm for light loft storage - especially of you screw ply or T&G chip down at regular spacings (but think how you will get to your wiring - I'd use ply meself and I would not glue it (even though it would be a strength advantage).

You can fix your new joists to the old ones at every intersection with TimberLok or Reisser screws - basically rally long screws that can be driven through the top joist into the lower by an electric drill or suitably meaty power driver.

How are you for headroom?

[Skipweasel]

That would depend on how high you made the new floor, Shirley.

[Clint Sharp]

In message , Tim Watts writes

I agree entirely, benefit of hindsight and all that..

I think I'm going to have to accept some crushing of the insulation if I go this route but what I've not seen is any comment on my idea of hanging the flooring from the purlin using joist hangers..

Basically, the loft is enclosed by horizontal beams 2.5x8 front, rear and side the bottoms of which are about 2 inches above the top of the insulation. My idea was to affix joist hangers to this and run my 2x4s across the loft, supporting in the middle, a span of 2.8 mtrs spaced at

500mm then laying chipboard T&G loft flooring over them.

I know in the eyes of the green gods I have sinned, there was no insulation at all :( but what you say is fairly accurate yes.

I'd screw it down and mark the wiring locations in black marker, I'm not too bothered if I have to cut through the chip in the future, it's cheap and fairly simple to replace, to my mind the hard bit of the job is getting the joists sorted? 500mm fits nicely for the loft, a midge's over 3 metres long by 2.8 wide.

Will be OK for the boxes but putting them in means bending double after adding the floor so it's only ever going to be storage space unless I win some serious money (at which point I'd move anyway)

[Clint Sharp]

In message , Clint Sharp writes

Right, it's all done, joist hangers off the purlin beam, front and back,

4x2 joists supported in the middle on the top of a wall and boarded over at 50cm intervals, lovely and solid, no discernible movement and no crushing of insulation at all. Anyone interested in before and after pics?

[nahalnyi.malyi]

[Rob]

Pictures are always appreciated

[Andrew Gabriel]

Haven't seen him here for yearly 4 years.