loft conversion - new roof trusses best option ?

[davidnow]

i have just purchased a 3 bed victorian terrace which needs a full refurb and i am not living in the proerty.

it will need new electrics , damp proofing, new ceilings et al.

it also needs a new roof covering.

given the location, it would not be worthwhile adding a loft conversion if the house was habitable and had a decent roof.

however, given the need for new roof, and the house will be like a building site, i think it may be worth going into the roof.

from what i read online, the usual metod is to put steel rsj into party wallls, suspend a floor, then put velux in roof.

but given the need for new roof covering, might it be better to totally remove roof, and install new 'room in roog RiR' trusses , giving floor without need for steel and then get new roof tiled ?

together with a trusted colleague, and known tradesmen, i can take care of all joinery, plastering, plumbing and electrics etc, but not laying the slates etcc to roof.

any thoughts or comments appreciated.


what i read about RiR trusses all seems to be biased towards new builds.

are they suitable as replacement roofs, and can they be used on a victorian mid terrace ?

if they can, i guess i wouldnt need to put steel in party walls, so would i still need party wall agreement for RiR install ?

 

[freddiemercurystwin]

Its an interesting concept and I would be interested to see how the numbers would compare. Though there would inevitably be additional works in fitting a whole new roof structure to an old property eg in levelling up the wall plates for example. Also as its a terrace it would need some very cautious measuring to ensure eaves and ridge lines all lined up with neighbouring properties. Modern trusses are built very accurately. Victorian houses were not.

 

[willismp]

Hi,

Last year we had exactly the same decision to make. In the end.

New trussed roof cost £20k all in for a waterproof structure. Inserting steels, doubling up rafters etc £30k. (It was a large roof).

Also for me I benefitted from -

Much more space, designed specifically to be an attic roof, so no risk of spreading ad all new graded timber. New felt, we did replace all the wall plates so got them level (ish) the house ran out, we lost 55mm over the length (the truss firm accounted for this in there design).

For me as the roof covering needed replacing it was by far the best decision, although a right mess and scary when all off!

 

[davidnow]

Thanks of both replies, sounds like it may be possible but not straightforward.

Willismp, Interesting to hear that full roof replacement was the lower cost option, can you confirm that your property was a mid terrace ?

Also,

Were those figures for a main contractor to take on the full job, design, regs, calcs and build, or were they culmitive costs using various trades ?

Did waterproof structure include any attic floor , dry lining etc ?

 

[willismp]

Hi, no it was detached, but the first of two roofs, i.e. we built this one, then added an extension to meet it. It also had three hips and two valleys so complex. Maybe a mid terrace would be easier just cutting timber, why not get quotes?

Mine is just a structure as we use subs

 

[davidnow]

I rang a couple of truss manufacturers and outlined my idea.

They both thought it might be possible, one of them more positive than the other.

However , I was a bit surprised at ballpark costs mentioned.

£5000 for supply of trusses with calcs.

house is approx 6m wide and 9m deep.

assuming a truss every 600mm , that would be 11 trusses with span of 9m.

a few hundred for design and calcs and a hundred for delivery maybe, still works out about £400 a truss.

Beginning to think we got wires crossed or I am missing something.

Anybody like to suggest ballpark figures. There are no dormers etc.

 

[freddiemercurystwin]

My ballbark figure would be £5000.

 

[davidnow]

thanks, how would you break that down ?

 

[freddiemercurystwin]

Its a ballpark, until they get a drawing to quote from you're just another punter phoning up for a ballpark figure and sensible ballpark figures tend to err on the side of caution.

I do seem to recall a rough rule of thumb that was based on about £30/m² for standard roof trusses and that figure should be doubled for attic trusses. So that gives you about £3300.