Newish build - trussed roof loft space for storage

[YorkshireMartin]

Hello guys and girls,

I'm in the middle of converting our somewhat non-existent loft space into storage. I just thought that before I do anything too permanent, I'd see if anyone had any comments to make on my strategy, as many of you here are vastly more experienced than I.

As our house is one of the new fangled 3 storey jobs where the top bedroom is basically the loft space, I'm not left with much to work with. Storage is always a problem in these houses and I thought if I could manage to board it out, we could sneak a few boxes of things up there without the danger of falling through the ceiling.

My plan is as in the picture, I'm running 38x63 C16 perpendicular to the joists, which are substantial (to my surprise). The C16 beams will be at 450mm centres, which I think is correct for supporting 18mm MDF, which I intend to use as the floor material.

Does anyone have any observations perhaps?

Pic attached of current situation.

Many thanks

 

[TFrench]

You can get chipboard flooring in small enough sizes to get through a loft hatch, might be better than MDF? In my garage I added some horizontal bearers to the trusses to create some shelves as well.

 

[RobinBHM]

Im not sure mdf is the best, its heavy and may sag over time, especially if it gets damp.

What about chipboard glooring or sheets of osb3?

I do hate modern truss roofs that dont leave any decent clear space

 

[YorkshireMartin]

You can get chipboard flooring in small enough sizes to get through a loft hatch, might be better than MDF? In my garage I added some horizontal bearers to the trusses to create some shelves as well.

I saw those loft boards in B&Q. My concern with them was that I'm so limited on placement, I dont even think I'd get two to join together in the gaps without cutting both rendering them somewhat pointless. So I hatched a plan to batch cut MDF to size with the TS55. I've just put in a new loft hatch but size is definitely an issue. I can't get full runs up at once as they are almost 3 meters. I'm going to try a 60/40 cut with a test board. If I had a larger unobstructed space, I'd definitely have gone with the loft boards.

Thanks for the idea about shelving on the trusses. I really want to max out the space, within reasonable loading params.

 

[YorkshireMartin]

Im not sure mdf is the best, its heavy and may sag over time, especially if it gets damp.

What about chipboard glooring or sheets of osb3?

I do hate modern truss roofs that dont leave any decent clear space

Do you think they would sag even with 450mm centres? It's actually a bit less as thats to the centre of the beams. Loading won't be too high. Not planning on putting a library up there. Damp isn't really an issue as far as I can tell, there seems to be plenty of air flow and the rooms below have velux windows, although it is warm up there. Is there perhaps a source of damp I havent considered?

 

[ComfortablyNumb]

Mdf will absorb moisture and weighs more. 18mm is overkill I think the chipboard is about 13mm iirc

 

[sunnybob]

I've boarded out a couple of lofts.
Chip board flooring is completely adequate and weighs a hell of a lot less than MDF.

Buy the small interlocking boards purely for ease of getting them through the hatch. Interlock if you can, no big deal if you cant. If youre going right to the edges allow a small expansion gap. Careful cutting to keep the ends on the cross joists and you wont even have to nail it down.

 

[petermillard]

Yep, 18mm T&G chipboard loft boards were made for this, much lighter than MDF and perfectly adequate for the job. Be aware they're not T&G all round, just on the long sides.

 

[Benchwayze]

Yorkie,

That's much the same as my loft space was when I moved in to my drum.

I enlarged the loft hatch, by reinforcing the rafters., and then cutting away the plasterboard and sections of rafter to enlarge the hole. I trimmed it, and boarded out with floorboards. I bought a loft-ladder from 'Do-it-all' (and am I glad I did, 'cos I certainly couldn't get up there now, like I did way back then, off a step ladder!)

What I didn't do was build proper shelving among the rafters and trusses. I just put boxes of stuff up there. Over the years the boxes got moved around and some of them split or burst open. What I had after a few years was a glory hole. I got rid of most of the stuff, but still never got round to shelving it out properly. (Just book storage at the gable ends. )

So don't make the same mistake is my advice!

I would suggest dividing a couple of the spaces between the verticals, by panelling them out on one side, to make small spaces, into which you can put shelves, and fit doors. Some conduit would make clothes racks for spare garments you don't wear often and don't want to ditch. Make or buy a stout trunk; even two. (On castors, they are better than drawers and quicker to do.) for some of the small stuff, and of course, make sure you have good lighting. And PLEASE! Fit a safety rail around the hatch. You know why I advise that! :mrgreen:

HTH

Edit. That was 45 years ago btw, and I got hold of some 'reject' floor boards, the stuff with loose knots, and split tongues and grooves. So it was much cheaper than it would be today, even allowing for the waste. But I am glad I went to the trouble. Even back then chipboard was a bit 'cr@ppy'.

John

 

[sunnybob]

John, dont confuse ordinary chipboard with chipboard flooring. The flooring has come on a long way in 45 years. Its all resin bonded and immensely strong and quite lightweight for lifting above your head..

 

[Lons]

Just a note of caution. Though I have been guilty of storing far too much in my own loft at times, as a now retired builder I was well aware of the possible risks (makes it even worse )

Modern trussed rafters are very carefully sized and designed to carry the specific load of the roof which comprises:
1). The rafters and bracing istself
2). roof tiles (normally based on interlocking concrete)
3). plasterboard and skim ceilings
4). Ancillairy fitting such as pipes, tanks, wiring etc.

Typically the bottom chord of a truss is designed for a superimposed load of 0.25 kN/m2 and the loadings are often compromised by builders who occasionally fit heavier tiles than design limit and plumbers / electricians and householders drilling through timbers as well as altering the trusses structurally which renders the design useless.

Surveyors and building inspectors are aware and are instructed to be on the look out for existing roofs that seem to have substantial amount or significantly heavy items stored in them. Books and paper in particular create high loadings.
Fitting loft boarding although it gives additional bracing adds to the load and more importantly encourages the storage of heavy items.

Not saying don't do it, just be aware and be sensible. There will no doubt be the usual cries of "rubbish, done it for years no problem" but if you do some research and you'll find what I say has some substance.

cheers
Bob

 

[YorkshireMartin]

Thanks guys for the input.

I've been trying to calculate the density of each material. I'm putting it here because I couldn't find the comparison anywhere else.

A sheet of 18mm MDF usually weighs between 40 and 50kg depending on the manufacturer. It covers 2.88sqm. A pack of 3 loft boards weighs 15kg and covers 1.17sqm according to Wickes, making it roughly 13kg/sqm.

I make the density of 18mm MDF to be a maximum of 17.36kg/sqm or minimum of 13.88kg/sqm. The real figure is likely to be somewhere in the middle I suppose.

Price wise, the MDF I have seen is £5.03/sqm and the loft boards are £5.68/sqm, so the price difference is negligible for such a small area.

I can definitely see that MDF has the potential to absorb moisture though. I just find chipboard harder to work with than MDF and I suspect the installation might be fiddlier than cutting full sheets to a snug fit. Bit of a trade off.

I think I'll check to see what the moisture content of the joists is before proceeding.

Tips on overloading noted, thanks Bob. I've done a visual check across the ceiling and door frames looking for tell tale signs of shifts in the joists. We've been walking about up there for a few years and I weight about 100kg so I think I could safely risk a quarter of that per sqm or roughly 10kg/sqm of storage plus floor weight.

On a related note, does anyone know how to identify if a roof truss is treated or untreated?

 

[Benchwayze]

John, dont confuse ordinary chipboard with chipboard flooring. The flooring has come on a long way in 45 years. Its all resin bonded and immensely strong and quite lightweight for lifting above your head..

Aye Bob.
I grant you that. But I like floorboards.
I also agree with you. Chipboard is just about fit for walking on! :lol: :lol: :lol:

Point taken re the 45 years time-warp though! I'll use it in my new shed!

Cheers
John