Loft converstion, point in the rigth direction

[elliott276]

Hello all

I am new here but everytime I do a search about loft conversions I seem to end up here. Little bit of back ground. Taking on a loft conversion is right up my street, this is not my first DIY project by any shape or form but it obviously takes a lot more planning as essentially it is structural.

I have read most posts to do with Loft conversions but still I don't seem to be able to answer my questions. SO I though I would post them with a fewpiccies to see what people had to say.

So as you have guessed from the title I am planning a loft conversion. I am still in the early stages and need some help.

I have the stairs sorted now and once built and installed they will comply with building regs. Next step for me is the floor and new joists which need to go down in the loft to make it load bearing.

This is where I am stuck, I have had a good rummage around in the loft and can't seem to find the best way to acheive this part. Some info for you:

The house is 8 meters from front to back. It is at least 7.5 meters from party wall to party wall. The aim is to get a double room and a bathroom up there which given the amount of space should be easy. Just need to get this floor right. The construction of the foor space looks like this:

Loft Area:
http://www.diynot.com/network/elliott276/albums/11530/43258

Rafter Support:
http://www.diynot.com/network/elliott276/albums/11530/43256

Supports:
http://www.diynot.com/network/elliott276/albums/11530/43255

Floor Joists:
http://www.diynot.com/network/elliott276/albums/11530/43257

I have read about two options. The first to slide in new flor joists from either the front or the back of the house which will sit on the front and rear walls, they would need to span 8 meters and I am lost as to what size the would need to be?

The second to install steels between the party walls just above the existing floor, this would give a base to which I could install joists and construct up from here.

So any comments welcome, I look forward to your response.

 

[freddiemercurystwin]

Joists to span 8m would be humongous and that would make it an uneconomical solution (a rule of thumb would be the depth required being about 1/20th of the span so 8÷20=400mm deep) not to mention actually trying to get 8m long joists into a loft if you could even find somewhere that sold them.

It will be cheaper and easier to fit a steel beam front and rear directly under each purlin just above your existing ceiling joists and span your shorter timber joists between the steels. A structural stud partition would be built off each steel to support the purlins. Each steel beam can be made up of 3 or 4 smaller ones and then bolted together once in the loft.

 

[elliott276]

Thank you for your reply.

I understand what you are saying about the 8 meter joists. So what are my next steps?

Structural engineer to do the steel calcs? Should I get the Building inspector involved at this stage?

Been reading about planning permission and it seems a bit grey, from what I have read if your loft conversion is above a certain size you need to get permission, is this correct?

If no permission is required do I simply inform the building inspector and then start the work or do I have to wait for him to instruct me as to what to do at what stage for sign off?

 

[stuartturbo]

just been on a search as i did think about them
http://www.telebeam.co.uk/

 

[stuartturbo]

Structural engineer to do the steel calcs? Should I get the Building inspector involved at this stage?

No the Building inspector doesn't care.Get a draftsman and SE, but get them to apply for Building regs as it should speed it up, any questions the Building inspector has etc

Been reading about planning permission and it seems a bit grey, from what I have read if your loft conversion is above a certain size you need to get permission, is this correct?

Yes there is limits depending on house size

If no permission is required do I simply inform the building inspector and then start the work or do I have to wait for him to instruct me as to what to do at what stage for sign off?

Apply for Building regs if no planning required.
They pass it off.
You start work.
Call them to make a visit.