What to do with this loft space?

[Molsy]

I’ve moved into a first floor maisonette with a well endowed loft space and I have a few Q’s.

I’d like to top up the insulation and build a sturdy floor that so I can safely walk around up there without any vibrations on the ceiling joists.

I plan to build a 6x2 subframe floor onto the existing beams (see pic) which are supported either end and midway by a supporting wall, top it up with 200mm insulation and then board it with plywood.

What can I do about those horizontal ties?

The plumbing and electrics will be below the subframe. Is that acceptable?

Any help is appreciated as I am not experienced in these matters!

TIA

Red line indicates where floor joists will rest

close up of tie - nailed into purlin and rafter

 

[catlad]

Looks like a 50's construction, what's on the roof?
My guess is tiles which will be heavy.
Short answer no you can't remove things.

 

[Mottie]

I’d be interested to find out about removing those horizontal ties - I have two in my loft that are a pain to climb over. What do they do? If they can’t be removed, how do they make a loft conversion - there’s a couple of houses down my street that have loft conversions so they must be removed on those.

 

[Molsy]

Looks like a 50's construction, what's on the roof?
My guess is tiles which will be heavy.
Short answer no you can't remove things.

Thanks for the reply catlad. Good guess, it’s early 1960’s. The ties are low down which makes me think they might be to support the purlins in some way but still not sure. Ideally like to raise them higher... If they’re just stopping the roof spreading I maybe replacing them with collar ties high up but thought someone here might know.

 

[leegsi]

I’d be interested to find out about removing those horizontal ties - I have two in my loft that are a pain to climb over. What do they do? If they can’t be removed, how do they make a loft conversion - there’s a couple of houses down my street that have loft conversions so they must be removed on those.

They would have added an RSJ at the ridge of the roof to take the weight of the roof.

 

[Molsy]

... there’s a couple of houses down my street that have loft conversions so they must be removed on those.

Yes, apparently it depends on what function the tie have. I spoke to a builder friend and it seems that some may be supporting the purlins and others stopping roof spread. If they’re stopping roof spread we may be able to raise them up. I think the rule is to put two ties in for every one you take away. Needs to be seen by someone who knows exactly what they’re looking at before any work can be done!

 

[Leofric]

I think the rule is to put two ties in for every one you take away. where does that rule come from Needs to be seen by someone who knows exactly what they’re looking at before any work can be done!

- agree with that

 

[Nige F]

I’ve moved into a first floor maisonette with a well endowed loft space and I have a few Q’s.

I’d like to top up the insulation
TIA

Is the maisonette leasehold ? If so you can only top up the insulation - the roof is the freeholders.

 

[Molsy]

Is the maisonette leasehold ? If so you can only top up the insulation - the roof is the freeholders.

Thanks for the reply, Nige. I have all necessary freeholder’s permissions to do any works I see fit (including velux windows when money permits!) . I’ve spoken to a structural engineer who’ll visit after all this corona-hysteria has passed. Will post results.

 

[Leofric]

What do they do? If they can’t be removed, how do they make a loft conversion - there’s a couple of houses down my street that have loft conversions so they must be removed on those.

Proper loft conversions are done by specialist companies or to a design by a structural engineer installing steelwork to compensate for the removal of structural timber components from the roof. However it is done it requires building regs approval and you can't 'just remove' roof timbers.