Loft Conversion - Advice

GaryJ_3

Found your advice very informative Richard.

I have a 1930's 3 bed semi with a hipped roof, and had some plans drawn up 2years ago for a basic loft conversion consisting of a single bedroom, the stairs were open from the 1st floor into the loft and a partition & fire door at the top. I have since decided to amend these plans to put the fire door at the bottom and the loft can then be open plan (making the loft visually larger). Similar to your quote, the loft floor joists sit on the wall plate at one end, a bearer bolted to the party wall at the other, then on a structural wall in the middle overlapping the joists and bolting them together. This wall is constructed of brick but is offset from the wall below it(ground floor) and is built on a rsj spanning 3/4 of the length of the house front to back as originally built. Do you think this may be a problem and was possibly an oversight of the architects? The original plans did pass building regs but they don’t show the position of the ground floor walls, just the 1st floor. I am renovating the property and currently the 1st floor ceilings are down and think this would be the best time to fit the loft floor, I was considering lowering the new loft joists by a brick height so that the loft space height slightly greater than it would be if I didnt.. on the party wall I was going to bolt a timber bearer with joist hangers to support the floor joists, but at the other end the bottom of the floor joist would be level with the bottom of the wall plate, I’m not sure if fixing a joist hanger onto the 4" wall plate would be sufficient for a 75mm width joist, any advice?

Derry_Rhumba

For anyone looking to draw up your own plans, Google Sketch-up is an easy-to-use package for producing 2d and 3d models.

http://sketchup.google.com/

Best thing about it: it's free
Worst: its fun, addictive, and you'll sepnd more time playing with it rather than concentrating on your loft.

boysmum3

An unashamed bump here.......
We are hoping to start our loft conversion on our victorian terrace in April - builder is a close friend who has done a few LC's lately so no worries there...the plans are drawn by the same guy that did our kitchen plans last year.
Problem (well niggle really...) is he is a architectural technician so although fully qualified to draw the plans he can't do the structural calc.
He passed everything on to a SE he knows who has ignored my recent emails re doing the job (we went on hold for a while cos of christmas and illness)...
my question to anyone is are you a structural engineer - do you want the job. :rotfl: I have phoned some one else but I get the impression as it is a tiny job, they're not right bothered...no return of calls etc!!
Joking aside - I would appreciate any advice, I am assuming someone would just need a copy of my plans to do this???

HappySad

I suppose that you have asked your builder friend to recommend someone? What about visiting your neighbours in your area and knocking on their door and asking if they could recommend a surveyor and why.

RICHARDGREENLAND

It probably won't be a problem for the loft floor to rest on the brick wall below, even tho this rests on an RSJ, as the brick wall itself will likely be much heavier than the timber floor and the contents of your room, and the RSJ should be designed to withstand this with some margin. But if you are unsure I strongly advise you to seek advice from a structural engineer who would be able to give you a difinitive answer for a few quid.

You don't need joist hangers to attach joists to a wall plate, but Jiffy hangers, which are thinner, more flexible and attached to the wallplate by means of multiple galvanised and ridged nails, or if you really want to go overboard, screws. You also have to make sure that your wall plate is sound and securely bolted to the wall, unless it is resting on top.

Sounds like you might benefit from a few days from your friendly local builder to get you out of the woods here - !!!!-ups at the early stages of a project can end up costing a lot more in the long term, and believe me, I 've seen a few.

Rich

GaryJ_3

Thanks for the advice, My wall plate is just bedded on the wall with the hip roof trusses bird nosed onto it. When you say bolted to the wall, do you mean by fitting restraint straps to the wall plate? if so 2.5mm or 5mm?

lynneinjapan

Ian.nb wrote: »

You will need to change every door that opens onto the escape route (practically every door in the house) to a half hour rated fire door, fitted with intumescent strips.

When I had mine done (summer 2005) I only had to get door closers put on all the existing doors - the only one that had to be a fire door with the intumescent strips was the new one leading up to the loft. The door closers are unobtrusive little things - basically a spring-loaded chain set into the side of the door between the hinges, not the big heavy arm over the door that you get in offices and the like.

HappySad

I have a arm system on my fire doors that all lead into the hall. they are small white and have a small arm and not where near the size and of those big office door closers.I am really happy now with my new loft and it looks fantastic :0)

kisk

We had a loft conversion about 8 years ago carried out on a semi detached bungalow. The house had been designed for future conversion but since the house was 25 years old the regs had changed. There was a gable end window and large open area.

We got plans drawn up by an architectural technician who had an engineers report carried out by a third party. I felt this was the way to go as some of the conversions in and around our street had noticeable sags on the rood ridge especially the house opposite mine as I could not help always looking at the line of its roof with my venetian blinds.

If you get proper detailed plans drawn up this can save on extras later on. The extras are a contractors dream as anything not priced for will make up for a low quote. This can be anything from cupboard shelves, woodwork finishes etc. Think about all the details you want to add to the conversion. Our conversion required steel beams to be installed with steal support struts going down through existing stud partition with the end fixed to pad stones. New joists run between steal beams to support upper floor.

We ended up with master bedroom with on suite shower room and a further double bedroom. Did not go for dormer windows as I don’t like flat roofs and roof could not allow any other design. Cost us £15,000 and was very happy with final results.

Make sure your existing boiler or heating system can support the additional space. The very worst part of our conversion was having a 3mm skim of plaster to the ground floor roof in every room. This was to do with fire regs and the existing plaster being 9mm when it requires to be 12mm. Very messy.

Kisk

GaryJ_3

Hi Rich,
Ive been trying to get things moving with the loft conversion. Im going to speak with building regs next week because although I have had plans approved by them I have decided to move the stairs slightly, well bout 2 feet as some neighbours (identical house) have had there loft converted and the stairs were in a better place. The only difference with their loft floor is that the joists are independent of the ceiling joist where as because i have no upstairs ceilings my floor joists are to support the ceiling below and the floor above. My biggest span is 3.8m so building regs have ok'd me to use 75x170 joists, using 75mm to keep the depth as low as possible. Because the joists are going to rest on the wall plates which are in turn sitting ontop of the inner skin outside wall I have checked out the levels at both ends and the wall plates do run out of true, bout 25cm over the front to back distance of the house. would it be normal for me to follow the existing out-of-level wall plate? i mean its straight but just not 100% level. Taking reference from the high point would i expect to level things up with packing as 25mm packing is excesive dont you think?
Regards gary