Boarding garage loft for storage

TheCyclingProgrammer

I'm in the process of sorting out our detached garage and organising the storage in there.

Most of the storage will be metal racking across the back wall of the garage but I'd like to board out the eaves sections of the roof for light storage - bulky or awkwardly shaped things that don't weigh much like large empty boxes, some light plastic spare dining chairs, suitcases, Christmas decorations etc. All heavy items will be stored on the shelving.

My plan was to get some 18mm P5 flooring chipboard (the 2.4m x 0.6m stuff) and lay boards across the trusses on each side, leaving the middle section clear for ladder access (I will be access stuff in each "bay" from a ladder, I won't be climbing up there).

I'm unsure if this is likely to be too much weight for the trusses to take. I know trusses have a bit of spare capacity in them but I have no idea how much. The chords are approx 70mmx35mm, they span 5m and are spaced on approx. 600mm centres. It seems the heaviest thing I will be putting up there is the chipboard itself (the reason I'm thinking of using 18mm instead of 22mm is to keep the weight down).

Is this a really bad idea?

ssparks2003

to be honest i think you could go a lot thinner on the boarding to save weight and money. unless you are pinpoint loading the boards you could easily get away with 6mm ply if you are only supporting light items, a suitcase will be more than fine,

TheCyclingProgrammer

ssparks2003 wrote: »

to be honest i think you could go a lot thinner on the boarding to save weight and money. unless you are pinpoint loading the boards you could easily get away with 6mm ply if you are only supporting light items, a suitcase will be more than fine,

That might not be a bad idea. Even the 18mm chipboard works out at around 17kg a sheet, or around 7kg per m (0.6 wide). That's approx. 80kg of extra weight on each side on the boards alone.

I know plywood has a higher strength to weight ratio but would 6mm ply really support anything significant across 600mm centres? The idea was to store stuff in the bays between the trusses for easy access - nothing really heavy as I said but the weight would still be between the trusses rather than directly on them.

ssparks2003

I have used it in my garage with no problem, I added a screw into each rafter to stop the board sliding around and as long as you are not loading the very centre with excessive weight it should be fine. I have the large plastic lidded crates you can get from B&Q on them with no problem.

Furts

Standard truss roofs like yours will take cold water storage tanks and header tanks. These were the large black plastic tanks used before mains fed and combi boilers became more common. The Regs were iirr to spread the tank loading over 3 trusses using spreader timbers. Regardless, your trusses will take chipboard because this will be spread over 4 trusses. Just remember on 600 centres you should be using 22mm, though for loft storage you might take a flyer on this - depends if people can walk on the boards.

TheCyclingProgrammer

Furts wrote: »

Just remember on 600 centres you should be using 22mm, though for loft storage you might take a flyer on this - depends if people can walk on the boards.

Yes, I know 22mm is better for these centres but as it is just for light storage - there isn't the headroom for anyone to walk up there - I figured 18mm would be fine.

If they start sagging I'd take that as a sign I'm storing too much weight up there but I really am talking about furniture cushions, suitcases, empty boxes etc - the sort of stuff that takes up loads of room and doesn't really tidy away in boxes on shelves. I think the heaviest single thing I might store up there is our tent but that's still not that heavy.

I realise standard trusses are designed to take some additional weight, though I was wondering if there might have been less tolerance with these as they were made for a detached garage. AFAIK the trusses/roof is about 30 years old. The only markings I can see stamped on the trusses are "M75" and "SC5" which I think refers to the strength grading?

I wonder if a compromise might be to only run a single row of sheets on each side instead of two rows per side - the amount I could store on a second row nearest to the eaves would be severely restricted by the roof pitch anyway and I'd be halving the amount of weight straight away.

Mr.Generous

I'd use 12mm OSB as its just for shelving. Lighter but strong enough.

27cool

Bearing in mind that water weighs 10lb a gallon (in old money), so a large water cistern can weigh 500lb. Standard trusses can cope with this if it is spread over a couple of trusses

TheCyclingProgrammer

Well everyone on here seems a bit more confident, which is positive. If you read on some websites you'd think your roof was going to collapse if you looked at the trusses the wrong way - all sorts of talk about people adding separate joists, strengthening the chords etc. - lots of over-engineering going on there I think!

I've decided to go ahead, but as above I'm just going to lay a single row of 600mm wide boards on each side, leaving a gap closest to the eaves. This should give me plenty of room for my needs and will encourage me to try and spread stuff out along the length of the boards across multiple trusses instead of creating point loads in each bay between the trusses.

Thanks everyone!

Furts

TheCyclingProgrammer wrote: »

Well everyone on here seems a bit more confident, which is positive. If you read on some websites you'd think your roof was going to collapse if you looked at the trusses the wrong way - all sorts of talk about people adding separate joists, strengthening the chords etc. - lots of over-engineering going on there I think!

I've decided to go ahead, but as above I'm just going to lay a single row of 600mm wide boards on each side, leaving a gap closest to the eaves. This should give me plenty of room for my needs and will encourage me to try and spread stuff out along the length of the boards across multiple trusses instead of creating point loads in each bay between the trusses.

Thanks everyone!

Before you go ahead bear one point in mind. You mentioned P5 as your choice so I have not challenged this. P5 is fine in dry, warm locations like houses, but over time in a damp garage it will creep/sag. I have shelves in my garage made from chipboard offcuts and these have sagged, as has an old bookcase in there. Granted the centres are more than 600, but for total piece of mind cut up 18mm WBP ply, or if for very light use then 12mm WBP. I would not be looking at OSB.

getmore4less

I bet if you hung yourself from one of the trusses you would not notice it bend, easy 50kg + each. your boards adding less than 10kg