Looking to plasterboard loft. Please identify this wood structure.

[Tim Warren]

Hi All,

I have a mid 70s house with a good sized loft with enough head room for me to construct a model railway up there with my son. The loft was boarded out with chipboard flooring above rockwool insulation between joists by the previous owner who built the house himself (a builder by trade). There is also 50mm of foiled PIR insulation between the rafters and a 50 mm air cavity between PIR and the felt & tiles. So double insulated.

I wish to (partially) plasterboard the rafters so they can be painted white for light reflection and so that the ceiling can form part of the model scenics. The loft would only be used for the occasional hour in spare time so this is not a conversion.

There are a few timbers that are nailed to the rafters at an angle of 45 degrees which run from the outside corners in the eves up to the centre at the peak. I believe that these are only a temporary construction to prevent the trusses from racking during construction of the roof. They are only held in place with a single nail to the rafters with the exception of where the two timbers overlap which has two nails.

My question is: Can you confirm that these are not structural and could be removed to create a flat surface onto which I can plasterboard as battening out the whole length of the loft to box in those timbers would be a pain in the proverbial. Please see attached photo.

Thank you.

-Tim

 

[catlad]

No they are meant to stay there, but you could put some 11mm osb over the trusses which would then do the same thing. You could then plaster board over that.

 

[datarebal]

i would think you are planning to much weight up there on standard trusses

 

[Tim Warren]

i would tink you are planning to much weight up there on standard trusses

Not worried about weight. The model layout shall be very light weight (constructed with weight in mind and scenic made mostly from polystyrene or chicken wire covered with plaster bandage) and would be nothing compared to what was once up there - the loft is empty now. Floor is well supported from below too. Still, I shall measure for deflection with my laser measure to be sure. Recently boarded out the garage loft (as opposed to this loft above house living space) properly by getting rid of the previous owners "floor boards" made from old doors and kitchnen worktops and replaced with 18mm T&G chipboard. Measured for deflection from fixed points and could not detect any with my laser measure. The garage has a far larger span.

No they are meant to stay there, but you could put some 11mm osb over the trusses which would then do the same thing. You could then plaster board over that.

I was thinking the same thing should I need to maintain structural rigidity. Thanks.

 

[frutbunn]

You have a trussed rafter roof and the bracing is diagonal wind bracing and should remain in place if this is an external gable wall, although they are incorrectly installed in any case, so it would be wise to remove and refix them correctly,

 

[datarebal]

Not worried about weight

Cool! i forgot plasterboard is made of wire mesh and polystyrene

 

[KenGMac]

These trussed roofs are specifically "Designed" using computer software, the object is to produce a truss / roof that is the most "economic" and will be the cheapest to produce but meet all the requirements of the stresses the roof and all the trusses need to meet.

The Software will provide a [so called] nailing schedule, where every nail and gang nail plate MUST be fitted.

Likewise the wind bracing [ the timbers you are thinking of removing ] are specifically designed by the software.

In general terms, if you want to modify any aspect of this roofs structure you really need to consult the designer of the trusses.

OK seems a bit tough, but i have seen some real horror stories where a home owner modifies a single piece of timber and all hell breaks loose??

Ken.

 

[Tim Warren]

Thanks guys. I shall heed your advice.

 

[freddiemercurystwin]

You have a trussed rafter roof and the bracing is diagonal wind bracing and should remain in place if this is an external gable wall, although they are incorrectly installed in any case, so it would be wise to remove and refix them correctly,

So the roof has miraculously survived for 45 years with incorrectly installed bracing, do you really think it worth worrying about it now?

 

[frutbunn]

So the roof has miraculously survived for 45 years with incorrectly installed bracing, do you really think it worth worrying about it now?

Or they may have been removed very recently to fit the insulation boards and reinstalled incorrectly, either way its not a big deal to do redo.