Loft conversion advise

[timh81]

Hi, I am trying to save some money by doing my own loft conversion. Being lucky enough to have a large open loft with no struts to contend with it should be an easier job as no structural work should be required other than the floor and needing an electrician. I have decided to start my building approval plan for a loft conversion and have some questions regarding reinforcing the floor. I need my joists to run width ways due to the position of the stairs so I will need to run steel or timber beams down the length of the property approx 18 feet. How big will these need to be? I have read that a 3"x9" wooden beam would suffice providing its fire treated. Is this correct?

ManyThanks
Tim

 

[Leofric]

You will need

structural engineer's calculations for the structural alterations as part of the ​

Building Regulations application for the loft conversion so the SE will specify the joist sizes and support beams etc.

 

[tony1851]

I have read that a 3"x9" wooden beam would suffice providing its fire treated. Is this correct?

No it isn't; a 3" x 9" timber would be nowhere-near suitable. On that length you would need a steel beam - the SE will advise.

 

[^woody^]

I have read that a 3"x9" wooden beam would suffice

Don't read any more from wherever you read that.

BTW, the position of any stairs does not need to determine the direction of any joists

 

[Leofric]

​

Bear in mind there are more things than just structural matters to consider for bldg. regs approval if you are converting the loft in to a habitable room.

 

[Adam182]

​

Bear in mind there are more things than just structural matters to consider for bldg. regs approval if you are converting the loft in to a habitable room.

+1

I originally was going to try something similar, after researching and realising the many different building regs it pretty much killed the plan before it even started. The hardest one for me to get around was achieving the correct height above the staircase that was to be used for access.

 

[Leofric]

I don't like them and I don't know if it would be suitable for your situation, but you might be interested to look at Approved Document K which allows an alternating tread stair , only in a loft conversion for access to one habitable room - paragraphs 1.29 to 1.30 diagram 1.10.
You can view Bldg regs approved documents -just search under LABC.