hip roof loft conversion

[Chris Allmark]

I am looking at converting my loft (3 bed semi) into a bedroom. I know about all the building regs issues, & intend to do the job properly with a full-plans building regs submission. The problem is that the property has a hip-roof with quite a shallow pitch, so that the maximum distance from the top of the existing bedroom ceiling joists to the ridge plate is only about 2 metres, as it stands at the moment the useable area of the room will be so small as to make it not worth converting. Would it be possible to lower the existing bedroom ceilings to create more room in the loft, and/or install dormer windows at the back. The problem(!!!) with the dormer windows idea is that there are three large purlins running round the loft space which would be in the way. Would it be possible to remove the purlin at the back and replace it with some othe form of support for the roof? Has anybody done a loft conversion with these issues, or should I just give up the plan all together?

Thanks in advance, Chris.

[James Hart]

After doing all that it almost sounds like you'd be better with a new roof instead.

[Toby]

Considering each problem has a £££ solution, this may work out as an expensive conversion. The floors in the loft would be about 120mm higher than the existing level as your existing ceiling joists are likely to be a lot smaller than the ones required to support a floor. Installing 220mm joists lower down is a good solution and one commonly done on properties in this 1900s terrace with almost 3m room heights.

The dormer is a sensible option to create usable space, and a couple of well placed steels can solve most purlin problems.

[John Rumm]

I am just about to embark on a similar conversion - although I have a little more headroom under the ridge beam.

To get any real floor space you would need to convert the hipped roof to a gable end, and then stick a full width dormer on the back.

Having the hip away, and the rear dormer added, will get rid of two of the purlins for you. It is normal to build a dwarf internal wall to the front of the property (usually approx one meter high - that will likely coincide with the front purlin - thus hiding that.

The only major issue you will need to address is the available height (or lack of it). The new floor level will add 6 or 7 inches to the existing floor height - meaning a ceiling height of only 6' by the sounds of it. Sounds a bit low to me. How high are the ceilings in the rooms below?

[The Natural Philosopher]

I agree. Strip teh roof, upgrade the celing joist, and build a new one a bit higher with dormers. Buildin reghs otherwise will limit where the staircase etc can go so muh there will be nothing left to use.

[Chris Allmark]

Thanks to everyone who has replied so far. The ceiling height of the existing bedrooms is around 2.5m, so it would be possible to lower these by 30cm or so. As regards changing the roof from a hip to a gable - would that require planning permission as well as the building regs? If the purlins were removed where would the steels have to be placed ..... this all sounds like it is going to be v.costly and slightly beyond the scope of a diy project !!!

[Peter Crosland]

Almost cetainly.

If the purlins were removed where would the steels have to be

You will certainly need the services of a structural engineer to satisfy the BCO that the work will be safe.

[John Rumm]

I was pleasantly surprised to find out that you don't!

You can have a dormer at the back, and the gable wall conversion, and velux type windows to the front all without planning permission. The only time you will need PP is if you want to stick a dormer on the front as well.

Depending on the size of the place there is probably not that much need for steel work. The gable end and dormer obviously no longer have need of a purlin, and the one on the front can be extended such that the end left flopping about it taken to the new gable wall and hung from that.

It would be normal to put a RSJ/large timber beam in across the front of the existing loft to which the new floor joists will then be attached via joist hangers - but that would limit the amount you could lower the floor level even by "stealing" space from the rooms below. At the rear the new floor joists would be hung from the rear wall.

A good architect may also be able to draw up the plans and do the calcs required.

[Owain]

"Peter Crosland" wrote | "Chris Allmark" wrote | > Thanks to everyone who has replied so far. The ceiling height | > of the existing bedrooms is around 2.5m, so it would be possible | > to lower these by 30cm or so.

AFAIK there is no minimum headroom requirement for rooms but there *is* for stairs, so you might not be able to bring your stairs up close under a slopey bit of roof.

| > As regards changing the roof from a hip to a gable - would | > that require planning permission as well as the building | > regs? | Almost cetainly.

And is quite likely to be refused as the OP is in a semi, and the planners are likely to be unhappy about changing the shape of one side but not the other.

Owain

[Paul Boakes]

I think it depends on the area you're in. I've just done exactly this - a hip to gable conversion - with no problems at all from Harrow council. My architect, however, told that if I'd have been in Brent or Ealing - neighbouring councils - he would have been most suprised if planning permission had been granted. On the downside though, they did insist that the back wall of the dormer was 100cm up the roofline, and that the edge of the dormer near the gable end was brought inwards 100cm as well.

Regards Paul

[The Natural Philosopher]

There is. about 2.2m although its relaxable to an extent in lof conversions.

Correct, tho agian loft conversions have slightly relaxed sets.

[John Rumm]

1.9m at the centre of the stair rings a bell, can be less at the edges of the stair.

[Hugo Nebula]

On 15 Feb 2004 11:54:03 -0800, a particular chimpanzee named [e-mail] (Chris Allmark) randomly hit the keyboard and produced:

A hipped roof wants to push the walls out as load is added from above (wind, snow, etc). This is normally restrained by the ceiling joists forming a tie from one side to the other at wall plate level, the purlins and (hopefully) angle ties at the feet of the hips. By removing the ceiling joists and installing floor joists, the natural triangulation is removed. Further removing the purlin to install dormers will create an 'unbalanced' roof.

None of these things are impossible to overcome, but will require the advice of a structural engineer. As mentioned in another post, your best bet may be to extend the side to form a gable. IANAPlanner, but it will v. probably require permission.

[Hugo Nebula]

On Tue, 17 Feb 2004 10:29:15 +0000, a particular chimpanzee named The Natural Philosopher randomly hit the keyboard and produced:

There is no minimum headroom requirement in the Building Regulations (except that for stairs and landings) and hasn't been for at least 20 years now.

[The Natural Philosopher]

Mmm. Then why did my architect go nuts about making sure I had 2.2m height rooms throughout?.

Certainly you have to have rooms atleast 1.75 m tall,

to satisfy e.g. trickle ventilation that requires some

part of the vent to be above 1.75m from floor level...

..perhaps you are right, in that as long as your landing is 6 feet tall, and your doorways not much less, you can have a 1 inch high room, provided its not equipped with electrical sockets (450mmm minimum height) windows (mimum dimension for fire exit) trickle ventilation (min height) etc etc.

>

[Hugo Nebula]

On Tue, 02 Mar 2004 11:46:22 +0000, a particular chimpanzee named The Natural Philosopher randomly hit the keyboard and produced:

Correct. Your one inch high room could have ventilation via a mechanical ventilation system and your stair enclosure could be fitted with fire doors on the ground and first floor removing the need for external windows, and in any material alteration (such as a loft conversion) there are no requirements relating to the height of sockets.