DIY LOFT CONVERSION ADVICE

[craigb21200]

Hi,


I am in the process of doing a loft conversion


I have installed a velux and now want to do the floor.


I have a 3 bed semi and want to add a useable room.


The house is a 1950's build.

It is a 'cut roof' and has the joists running width ways with purlins and binders X2 the full length. There are two struts coming off the purlins centrally that meet in the middle (at a small block in the floor) there are also a few hangers.


I want to strengthen the floor and board it.


The length of the loft is around 17ft.

What i want to know is can i run additional wood along side existing joists off the wall plate was thinking 6x2 or 8x2

This would consit of a joist of 15ft from each end off the wall plate that overlap in the middle over the beedroom wall below (as they do now)
- so the joists would not be running across the total width of the loft which is around 22ft -

I will also need to take out the struts (and binders) after adding additional strengthening. Was thinking of putting additional 6x2 times 2 bolted together under the purlins and adding verticle supports. the 6x2's would rest on the new 6x2 joists.

I am not adding a dorma or bathroom,.

I will be getting a permanent staircase fitted in due course.

I have the following already :

Perlins x 2
7x2 16.5 ft long (cut into wall at one end not attached at the other.
Struts x 3 (each side)
4x2 meeting in the middle at a block on the loft floor
Rafters x 14 (each side)
4x2
Binders x 2 (1 each side)
4x2 length just under 16.5 ft (not attached to the wall)
Joists
4x2 spaced about every 14 inches
23ft total length (width of loft) but laid as two lengths that cross over supporting wall in the middle of the loft. (approx 11ft each length)
Cross members x2 (one at each end)
2x4 11ft approx attached to rafters ( was 3 but i removed the middle one)
Strengtheners x14 (span the top of each rafter) - I fitted these recently
2x4 (approx 25 inches cut)

The joists rest in the middle of most of the loft on a structural wall and onto the wall plate (i.e. on top of).

Any advice would be much appreciated.

 

[^woody^]

Are


building

control


involved?

 

[craigb21200]

Hi,

No...

I am on a tight budget so will not get them involved as yet.

 

[noseall]

Hi,

No...

I am on a tight budget so will not get them involved as yet.

When then?

You will need to get a professional involved with design at some stage so why not at this crucial time?

Surely the question should be can you afford not to?

 

[freddiemercurystwin]

Tight budget or not its a waste of time and ill advised to be adding anything to the thread unless BC are involved.

 

[craigb21200]

Thanks for the comments

I am just after some sensible advice that's all.

I have spoke to a few builders and also emailed the details and pics to a structural engineer...

I understand the comments but would like some meaningful advice....

I will be doing it myself and consulting / using builders when required.

 

[freddiemercurystwin]

You need to consult a structural engineer to provide you with a design that enables your new floor to work and provide support for your roof which may also need reinforcing! You are at that stage now! Not doing this at this stage is foolhardy and will cost you more in the log run, potentially a lot more.

 

[craigb21200]

Thanks but i am not a total idiot and have done some building work in the past.

For the change i am making i don't want to spend £700 at this stage on BC.

I do not need steel as i am not putting in a bathroom or dorma. I am sure there must be pleanty of people that have done this before so was just asking for some advice.

I appreciate the responses BUT would like to have a few with constructive comments.

All the best Craig

 

[freddiemercurystwin]

Well Sherlock, I've never done a lofty without a few steels so I guess my SE has been wrong every time!

Why you think a loft conversion only needs a few steels if it has a bathroom or a dormer is a mystery.

Ahh well you can lead a horse to water ........

All the best Freddy

 

[^woody^]

Craig, its allright wanting to save a few quid by DIYing, and you might have done some building work before, but despite that, are you actually making sure that you comply to all fire-safety regulations and ensuring that the loft is structurally braced?

There are loft conversions and there are safe loft conversions. So even if you are not getting it checked, is it actually safe? If you knew how quick a fire spreads, and how destructive it can be then you would be wise to get this checked/designed now. And yes, fires always happen to other people.

There are span tables linked from this forum or elsewhere on the net. 150mm joists don't seem adequate for that span, but that's as far as I'd like to go

Strengthening via struts is not the only consideration, you need horizontal bracing too

The need for steels has nothing to do with bathrooms or dormers

So perhaps, does this suggest that you do need to get someone involved to either specify or check your work?

 

[craigb21200]

ok thanks

have emailed the structural engineer so will await his response.

Just to add the joists would NOT run the total length. I would run them width ways overlapping in the middle over a structural wall below.

 

[freddiemercurystwin]

ok thanks

have emailed the structural engineer so will await his response.

Just to add the joists would NOT run the total length. I would run them width ways overlapping in the middle over a structural wall below.

Yes and BC will expect confirmation from your SE that your existing wall can take the additional loading.

 

[catlad]

In a small village near me 3 months ago a fire in a converted bungalow killed three children and a 18yr old lad. The smokedetectors had no batteries in, instead of being hard wired, a tragedy, and thats one reason why people will not give advice.

 

[craigb21200]

I must admit i thought that was the point of this forum - Advice that is ...

And it is a DIY forum.

As i said i appreciate the comments but would have really like a few pointers too........

 

[^woody^]

Helping someone put a shelf is one thing. Helping them with an unauthorised and potentially unsafe loft conversion is another

The pointers are in this thread