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Roof Extensions

By: Chris Hogan MSc - Updated: 15 Nov 2010 | comments*Discuss
Roof Extension Loft Conversion

Loft conversions give you a very good return on your investment but sometimes there isn’t the roof height at the apex, or width, to give you enough headroom for a usable space. One option that can resolve this is a roof extension. This is where the roofline is extended to the outer walls of the house, a bit like a full width dormer window.

The Investment Potential of a Loft Conversion

Extending into the roof is one of the best projects for a renovation because you can add a bedroom (or two) and possibly a bathroom as well. Because of the way that houses are valued in the UK this will push your house up into the next price bracket.

But you don't have all the building work required for an extension on the ground, like excavating for foundations, drain re-routing, then building the foundations, walls and ceiling. There may need to be some strengthening work done to the loft floor and some re-jigging of roof supports but that isn't anywhere near as labour-intensive and expensive.

All you then need to do is put in stairs and dormer windows or rooflights. The rest is interior fitting and finishing which you would be doing with an extension on the ground anyway.

Roof Extension Economics

If your loft isn't the right size or shape for a traditional loft conversion with dormer windows or rooflights, then you may still be able do it but the line of the roof will need to be pushed out to give the headroom first. The cost benefits do change if you have to do a roof extension though, as there is a lot more work to be done.

Assuming you are starting with an apex roof, pushing the roof line out will involve taking away the rafters on one side. New side walls are built, an end wall with a window and then a new flat roof over the top. There needs to be additional support too, to replace the strength lost from the removal of the rafters.

This is a lot more work than a loft conversion on it's own, and that means more expense. It will almost certainly require the hire of scaffolding to the highest storey, and it means a lot more material coming up through the house or up the scaffolding.

Although the cost is greater, for probably little tangible extra return, if the alternative is a loft conversion with very low headroom which could put off potential buyers, the bullet simply has to be bitten.

Planning Issues for Roof Conversions

Anyone taking a train through the suburbs of any major city in the UK will be able to see why planners aren't that impressed with the majority of roof extensions. You will be able to see row upon row of houses built between 1850 and 1940, all with roof extensions of varying degrees of quality and beauty.

For this reason very few houses will get planning permission to put a roof extension on the front of a house. At the back there will be more leeway, especially if many other houses in the street have had them built already. Before making any plans it's essential to speak to the planning department, or an architect with previous loft conversion experience in the area, to gauge your chances of getting planning permission.

Structural Issues

The most critical point abut a roof extension is to make sure it is all structurally sound. It is utterly essential to get the opinion of a qualified structural engineer as the weight of the roof supports will add to the weight of the new floor supports and fixtures and fittings, not to mention the people using the room.

You can be more creative with a roof extension too. Even if you have the room for a decent loft conversion, a roof extension can open up more possibilities. For example if you aren't overlooked you may be able to have patio doors and a terrace on the roof – now that would really make a property more attractive.

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