Proposed loft conversion for my house

[sintra]

Hello All,

I am currently looking to convert my loft space into a bedroom and en-suite, at the moment my existing staircase is in my lounge. If i was to go into the loft and effectively then make my house 3 storeys high would i still be ok with my staircase coming down in my lounge ? It is my understanding that when you have a 3 storey dwelling you have to create a fire protected lobby with no exit through a habitable room, is this correct ? Also i am intending to put the doorway for the loft conversion on the first floor, not sure if this will help the situation or not. If my thoughts are correct can anybody think of any suggestions to get around it, one of my thoughts was to install a first floor fire espape window to the enclosed lobby area of the bedroom.

Also i am thinking of trying to as much of the conversion work as i can, obviously there are lots of aspects which will need the proffesionals for, but upgrading the rafters and the floor i thought i could do. At the moment my roof is made up of trussed rafters, i know this is harder to convert than a traditional roof but still achievable/

My initial plan of attack to get the loft structurally sound is as follows:

1. I will strengthen existing rafters with new 150 x 50mm timbers fixed to existing rafters.

2. Get a builder to insert new steel beams, 1 at ridge level to support rafters and 2 at lower level to support the bottom end of the rafter. Then a further 2 at ceiling level to hang my new floor on, at moment i have no solid walls and the overall span of the building is 6.8m so this would be to far to span a single joist. (Does anybody have any other thoughts on the new floor ?) My idea for getting the steel into the roof was to punch a small hole in the gable wall and slide the beams across, does this seem the best option here ?

3. Once all the steel was in place and the rafters have been upgraded i then intended to cut out all the remaining setions of the existing trussed rafter.

Does the above plan of attack seem like a good route and does anybody have any suggestons ?

Cheers

Darren

 

[Shytalkz]

Steels at floor level, with stud wall built off to support the rafters (for 6.8m span, 203x203UC will be probable size); ridge purlin (steel or timber flitch) may or may not be needed, depending on where studwork wall is placed relative to the span from ridge to eaves. Beams can be split with site splice bolted joints to ease getting them into the roofspace. Double up existing rafters from new studwork to ridge. Floor joists span between the new beams, alongside the existing ceiling joists.

 

[sintra]

Thanks for your quick reply Shytalkz

Double up existing rafters from new studwork to ridge.

So are you saying that i would not need to increase the rafter depth, at moment the rafter is 80x50mm the span from ridge beam to lower level beam would be approx 3.5m

Cheers

Darren

 

[Shytalkz]

Hmm, will struggle on doubling up on that kinda span, but is that up the slope or on plan? If the latter, allow the 150s and those in conjuction with the existing will work; if the former and the plan span is around 2.1m, then 50x100s with the existing will be ok. In both instances, provide 2x new rafters where trimming out either side for velux openings. Use C24 timbers in either case, better both in bending and for deflection.

 

[sintra]

I was talking about the rafters on the slope these will need to span 3.5m, the new floor joists would need to span 4.85m

 

[Shytalkz]

Assuming a pitch of around 40°, that's around 2.95m on plan, so 50x150C24s will be fine alongside the existing.

Joists spanning 4.85m will need to be 63x200C24 or 50x225C24 at 400, nogged at 1/3 span.

 

[sintra]

Thanks for the reply My sloping rafters will need to be 3.9 m in length as the roof pitch is 45 degrees.

It is my understanding that when you have a 3 storey dwelling you have to create a fire protected lobby with no exit through a habitable room, is this correct ? Also i am intending to put the doorway for the loft conversion on the first floor, not sure if this will help the situation or not. If my thoughts are correct can anybody think of any suggestions to get around it, one of my thoughts was to install a first floor fire espape window to the enclosed lobby area of the bedroom.

I am also considering using YBS superquilt 14 as my insulation has anybody used this, does it perform as good as they say it does ?? I have read lots of different things about it on the net and they are all different opinions so im a little confused now

Cheers

Darren

 

[Shytalkz]

The stairs to the loft need to either have a fire door at the bottom or the top. There are restrictions as to where the door can be placed relative to the stairs, which might affect your thoughts regarding placing it at first floor level.

MOE requirements have been relaxed/varied, I'm not 100% up on it tbh, someone else on here will enlighten you, I'm sure.

Multifoils such as YBS or Triso10 are currently a no-no on their own if you use a LABC - you can't be stopped from using it, but they won't give you a completion certificate unless/until the situation changes (or you use it in conjuction with other insulation), but don't hold your breath on that one. Private approved inspectors, whom you can use instead of the LA, may allow it though. 2L2 is a possible alternative which is not defined as a multifoil: www.thermal-economics.co.uk.

 

[sintra]

203x203UC

is this a standard beam size ?

 

[Shytalkz]

Yes. Comes in four different weights from 46 to 86kg/m.

ETA can't count: five.

 

[couldidoit]

Steels at floor level, with stud wall built off to support the rafters (for 6.8m span, 203x203UC will be probable size); ridge purlin (steel or timber flitch) may or may not be needed, depending on where studwork wall is placed relative to the span from ridge to eaves. Beams can be split with site splice bolted joints to ease getting them into the roofspace. Double up existing rafters from new studwork to ridge. Floor joists span between the new beams, alongside the existing ceiling joists.

Hope you don't mind me jumping in here but I have a question with regard to "site splice bolted joints" does the joint have to be supported? The reason for asking is that I am considering a loft conversion but all my internal walls on the 1st floor are stud partitions and therefore none supporting. To overcome this I've been looking at the solutions provided by Telebeam, they produce aluminium 'I' beams together with an extruded aluminium box beam that takes the weight of the roof and new floor, but of course they seem rather expensive. Perhaps a couple of steel beams would probably be a cheaper option but the span from gable to gable is approx 8.4m and there doesn't appear to be a practical way to place the steel beams of this length in the roof space without taking the roof of but if they can be joined then that may well be a solution. Your thoughts would be most appreciated.

 

[mointainwalker]

@ couldidoit

After twenty months I'm sure he's fairly relaxed if you jump in or not,

 

[freddiemercurystwin]

Esp as Shy's not a reg anymore!

 

[jeds]

This thread might be interesting.

//www.diynot.com/forums/viewtopic.php?t=137740

 

[couldidoit]

This thread might be interesting.

//www.diynot.com/forums/viewtopic.php?t=137740[/QUOTE]
Excellent! Thank you very much for the link.