Loft boarding structure - new build

[diy2020ask]

Hi, trying to decide which option to choose for raised loft boarding. I added loft photos, roof spec and some design drafts.

New build 2017, 'V' trusses, loft area approx 19m2 - 6.2m x 3m, joists 35x85mm, 600mm centres, boarded area span approx 3metres but it partly rests on load bearing wall. Insulation 300mm. Planned - medium Kg storage, Hatch should allow 600m boards, but for easier handling would trim 2400 to 1200. Due to hefty insulation plus air gap looks like would need one of those plastic stilts 270mm, as 175mm loft leg would compress insulation and would leave not air gap. Loft leg XL only come at 300mm which is a lot. Even thinking of just getting 45x70 C16 timber and just cutting stilts myself whatever hight needed, which also should be very cost effective.

House Builder came back with this:

Thank you for your enquiry, we can confirm your home is built and engineered to only take the weight of the materials currently used with the additional calculation for snow fall sitting on the roof within your build, we would not be in a position to offer guidance. If you are looking to apply alterations your appointed architect would investigate.

Got all necessary tools and quite handy, looking to do this DIY project myself.

Your thoughts and recommendation appreciated. Thanks

 

[PropRepairAdvice]

Your ceiling joists are only man enough to support the ceilings and not flooring/boards/storage unless properly strengthened. Get a competent builder.

 

[diy2020ask]

You may as well avoid commenting if you can’t say anything useful.

 

[PropRepairAdvice]

I see this time after time. If you do want you are intending you’ll cause your ceilings to sag, crack and at worst cave in. Good luck.

 

[diy2020ask]

Ok then, How would you execute this DIY project?

I doubt ceiling would sag unless extra heavy stuff stored.

If you look at photos, you’ll see span is 2m and truss bottom chord/joist rest on walls.

Truss is designed to regulations to take weight as minimum one person and storage 25kg/sqm.

uploading another design

 

[PropRepairAdvice]

Do you know that your ceiling joists will support the addition loads you’re imposing? Have you carried out the correct calculations? Do you know that the internal walls are load bearing or just partition walls (non-load bearing). I wouldn’t do this unless supporting the flooring off of the external and party walls. Take the advice from the house builder.

 

[freddiemercurystwin]

Ignore PropRepair fella, the joists will cope just fine with some light storage up there, what does he thinks happened when a couple of fat roofers were wandering around up there fitting the trusses? Ignore the housebuilder too, that's merely their stock answer. Stick some stilts up there or some additional joists perpendicular to yours to spread the load, have a search through the forum there are hundreds of threads on this very subject. https://www.diynot.com/diy/search/135354612/?q=stilts&o=relevance&c[node]=16

 

[diy2020ask]

PropRepair fella, this is for you - I think you did not read my post properly. Already told few times, yes span 2m - joist resting on one fully load bearing wall, another wall goes all the way to ground floor and rest on concrete flooring ( technically non load bearing).

Can you enlighten me on your calculations that you’re referring to?

Are you now telling that all them thousands of new build homeowners where companies boarded lofts on stilts should be worried? I doubt, or it just mean that boarding companies got no interest if ceilings will support extra load.

Attached another design.

So if you appear that knowledgeable why don’t you share some details how to execute this?

 

[freddiemercurystwin]

The walls won't be loadbearing that's the whole reason that trusses are used. It is possible they may appear to be and may be providing some loadbearing support but in reality you could remove all the walls and the roof would stay up there just fine.

 

[diy2020ask]

Freddiesmercurytwin, check this design


This design may make difficult to get longer timber battens through hatch and wouldn’t be able to cross layers of insulation. I don’t want to go over the top ££ and time wise. I will cut stilts from 47x50 timber

Agree trusses wouldn’t fail if all internal walls removed. Attached plan in the top post clearly show trusses joist being supported by load bearing wall + another wall, this surely should also take partly any extra load from storage in the loft. I was up in the loft and joist Do rest on wall top plates.

 

[freddiemercurystwin]

Of course the trusses are joined to the top of the walls, otherwise it would crack where the wall and ceiling plastplasterboards join. But the walls ain't supporting the trusses per se. I don't know where you found your image, it's merely something someone's knocked up on Sketchup. As mentioned joists perpendicular to yours to spread the load would be better than stilts, read some of the other threads.