Loft conversion potential

[Steve]

I live in an awkwardly built 1950s semi. However the loft is huge. It has massive potential. Our adjoining neighbours have told us they had a quote for a loft conversion and it was more expensive than the 2 storey extension they had built instead. When I look at the structure of the loft I see why it might be expensive, but wondered what the options are to clear the structure.

The left image is the plan. The joists and rafters run with the lined paper. The right image shows the cross section where the support lattice is in the middle of the loft. This lattice sits about 5 inches away from the chimney, and appears to transfer the weight from the middle of the 8x2 rafter supports onto the middle wall of the house. None of the other walls upstairs are supporting - all built onto the first floor with no support underneath. The lattice is constructed from 6x2s nailed together old school with 6 inch nails.

At the moment the left side of the loft is pretty much inaccessible.

So what can i do to eliminate this lattice support? Something is telling me the only option is to have a steel running front to back (shortest span) where the lattice is. This could then be used to support new joists (though would loose about 9 inch of headroom as theyd be at 90 deg to existing) Anything else that could be done? I appreciate this is not a diy job, just wondering what options are there.

 

[freddiemercurystwin]

Normally you would just run a steel beam along each side (where your 6x2s are) and build a stud wall off these to support the purlins, then hang your new floor joists off the steels, there's nothing complicated about this one.

 

[Steve]

Normally you would just run a steel beam along each side (where your 6x2s are) and build a stud wall off these to support the purlins, then hang your new floor joists off the steels, there's nothing complicated about this one.

The span is 6500mm though, wouldnt these steels be prohibitively big and expensive?

 

[freddiemercurystwin]

Depends on your idea of prohibitively expensive? Maybe something like a 254 or 305 deep beam @ say £50/m + 4 connections so prolly about £1k or so I'd hazard. You know your conversion will be say £30-40k + fees?

 

[Doggit]

If it's 6.5m side to side, what is it across the loft.

 

[Steve]

Depends on your idea of prohibitively expensive? Maybe something like a 254 or 305 deep beam @ say £50/m + 4 connections so prolly about £1k or so I'd hazard. You know your conversion will be say £30-40k + fees?

Yes I know its not a cheap do. But I was thinking of maybe making the loft useable/accessible for storage for now with a fold down ladder, then doing a proper conversion with windows, walls etc later on. The stairs into the loft will rise centrally to land about where the hatch is now (sacrificing the box bedroom below). I think with a full back dormer and 2 front veluxes I could get 2 bedrooms and a bathroom in (removing the chimney too).

If it's 6.5m side to side, what is it across the loft.

about 5.5m front to back. The central head height is approx 2300mm to the current ceiling joists.

 

[Doggit]

That's make it 2.7m from the central wall to the sides, so you might be able to use flitch beams to support the purlins.

 

[freddiemercurystwin]

2300? You'll be hard pushed to make that work without a very low ceiling even with a flat roof dormer by the time the floor is built and roof insulated, it's probably not a practical loft to convert, has anyone else in the terrace done one?

 

[freddiemercurystwin]

Here's a before and after section for a recent loft I did, personally I think the owners were nuts for pursuing it but Heyho, gonna be awfully cramped IMO.

 

[Doggit]

And as the new joists would reduce the floor height, that would make matters worse. I wonder if the neighbours quote was to reduce the bedroom ceiling height to increase it in the loft.

 

[foxhole]

Had a 6m steel as part of my renovation work, cost me £800 (mates rates) .Bunged a delivery driver £100 to sling it up in place while he was dropping off some blocks and sand.

 

[Ian H]

Had a 6m steel as part of my renovation work, cost me £800 (mates rates) .Bunged a delivery driver £100 to sling it up in place while he was dropping off some blocks and sand.

What size was that?

 

[foxhole]

What size was that?

Around 300mm “H” beam.