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Loft Conversion Advice

Discussion in 'off topic' started by Tenson, Nov 20, 2011.

  1. Tenson

    Tenson Trade: AudioSmile

    I will be moving in to a flat in December that has access to a loft space. At the moment it is simply boarded out, but I was thinking about converting it in to a usable extra room DIY style.

    I think a few of you might have experience with this type of thing, so I was hoping to get some advice about what is involved in doing a basic conversion?

    I've read that new joists need to be put in, as the existing ones are often not strong enough to be a 'real' floor. The look like 4x2 to me.

    There are struts going across the width of the space from one side of the roof to the other. There are also some struts from the roof to the floor. What is involved in removing these, and still supporting everything well?


  2. zener

    zener fluff

    Do not remove any of those struts , they are holding the roof up. This is a job for an expert. If you dont know what you are doing leave well alone.
  3. Still

    Still he said his naim was ralph

    Are you freehold or leasehold?
  4. andyoz

    andyoz pfm Member

    What about fire exit (seriously).

    Although, I guess if you are not sleeping in there there's a chance to bloody get the hell out of there!
  5. lutyens10

    lutyens10 pfm Member

    As Zener says don't move any of those struts. They are holding up the roof. The rafters, the roof timbers running from the top to the bottom, have been sized to span using that purlin, the horizontal timber, and its struts. If you move the struts even to wedge them vertically the roof will be seriously weakened as the load will not be properly transfered. Failure is inevitable at some point, potentially even from a heavy snowfall and its load!

    Potentially even more problematic is that the ceiling joists, the timbers that form the ceiling will never have been sized to take the load you are considering. They are usually only sized to hold the ceiling up and not much else!

    And Andy is right. You must always be able to get out of somewhere if there is a fire!

    Once you have sorted out your legal rights under your leasehold, as Still says, (you may have no rights to use the roof void in that way, or not without a payment), you must must get an engineer to check/design what you are proposing.

  6. deanf

    deanf pfm Member

    You might want to give the local authority a quick call and discuss building regulations - the conversation is free and you'll find out if what you're considering is legal.
  7. Tenson

    Tenson Trade: AudioSmile

    Guys I realise I can't just remove the supporting struts, lol! I assume there is a standard alternative way to support everything, since loft conversions are common and don't have beams shooting through the middle of the room?

    I also know that plans would need to be drawn up and checked with the council, and a fire escape route is needed.
  8. sojourner

    sojourner pfm Member

    That's an interesting pair of pictures.

    There is old (dark) and new (light) wood. I wonder why someone felt it necessary to add the new struts and cross pieces. I would look for evidence of previous movement or inadequacy in the original structure before doing anything else. I also wonder, given it's hidden by the insulation, where the new struts bear to - hopefully there is a wall under there and not just ceiling joists!

    More generally, ceiling joists are typically 3 by 1 and are not suitable to carry a floor. If you're unlucky and don't spread the load you might crack your ceiling by walking carefully around in the loft even. Building regs require certain sized joists to carry the floor depending on the span. Even at these sizes the floor can feel a bit springy and you might be happier moving up on size. The joists also need to be carried on a suitable bearer that will support the load and keep the new joists above the top of the seiling (even under room load deflection). Think steel joists if you don't have a suitable bearer already.

    Legally, there have been a couple of cases lately where people did this themselves and the roof later collapsed - obviously with the potential for serious injury or death (or being sued if it's not your house - anymore). (Hence bBuilding regs approval is a requirement if you sell it as a room later and good sense for your own peace of mind.) In these cases there were calls for the law to be extended further and the individuals I involved eitehr ended up in court or at least publicly censured.

    Best advice is to ask someone you trust who knows what they're doing. It's not rocket science, but getting it wrong could have serious consequences:)

  9. sojourner

    sojourner pfm Member

    Ah, as per my crossed post - steel joists running along the roof. Modern houses are even worse as they have the truss joists that have triangulation int he middle and virtually require a new roof structure as well as the floor/dry-lined walls.

    Our conversion was relatviely low key, didn't need steel due to much lower and very generously sized purlins and measures about 9 by 11 feet plus stairs landing and room recess. It makes a good study/photo room.
  10. blossomchris

    blossomchris I feel better than James Brown

    The added pieces would most probably have been a condition for mortgage etc. They would have been there originally and renewed except for the low collar brace that would have been a stipulation to prevent spreading
  11. Rodrat

    Rodrat pfm Member

    If you want the lease checked to determine whether you can, let me know, my wife is a property specialist solicitor and she will have a look. For free although she doesn't know it yet.
  12. penance

    penance pfm Member

    You will probably need a structural engineer to provide calculations for required steels etc.
  13. stevec67

    stevec67 pfm Member

    You certainly do need someone who knows what they are doing. Some 15 years ago I looked at a terrace with a loft conversion, liked it a lot. Great area, nice house, quiet street. The triangulation had been taken out of the roof for a conversion and as a result the place was suffering roof spread. Costs to make good were £10k on a house that was £40k. Cue my solicitor telling me to run away. The house I bought wasn't falling down and I contented myself with a bit of boarding out.

    Boarding out is OK, and this may be an option if you only want storage space. Building regs last time I looked were such that any loft space had to have walk-on capability and stand a floor loading of something like 100kg/m2which means a safe loading of a 16st man every sq metre of loft space. Now older houses may predate these regs but they will stand you walking about on joists. If the plaster starts cracking under your weight, get the hell out of the place because it's falling down and if it's that bad then the roof isn't long for this world.
  14. martin clark

    martin clark pinko bodger

    Quite - there's a world of difference between laying some boards for convenient /incidental/ unheated storage - and creating a 'habitable room'. 2 or 3 orders of magnitude in cost, too!
  15. Tenson

    Tenson Trade: AudioSmile

    Thanks for the advice.

    It does sound like more work and cost than I had anticipated so I won't be doing it, at least at this stage. Putting in stronger joists doesn't seem too hard, looking at this webpage (, but strengthening the roof with steel is beyond me.
  16. Fox

    Fox The sound of one hoof clopping

    One other thing. In places like London. Builders who specialise in loft conversions will simply calculate the extra value added to the house and quote that, £30-£50K for an extra room etc. Its a growth area and has been for some time now as people decide to not move but go upward.
  17. mudlark

    mudlark nearly half a clue

    I know of a cottage that was "improved" as part of an improvement grant and now it has serious roof spread. I would guess that the cottage has lost £30,000 in value. Buggering up the roof structure is exceedingly serious.
  18. Rasher

    Rasher Quadrophenia land

    In the event of a fire, by the time you are aware of the smoke, you have two minutes to get out. Beyond that you and everyone in the house will die.
    I'm being serious.

    As a structural engineer I'm often asked to design strengthening works for unofficial rooms, and I usually tell them that the cost could be the lives of their children and refuse to have anything to do with it. I know I lay it on thick, but the risks are real.
    People often think that Building regulations are just hoops to jump through, but they are there for a good reason and protect people from themselves.

    Escape is usually onto the front roof slope by a roof window to be rescued by the fire services from a ladder. That is the normal consideration. If a roof window can't be reached by a ladder, you'll die.

    When these houses were built it was never intended to put people living in the attic, under the stairs, under the floorboards or in a cupboard in the back of the garage. Any extension needs careful thought and safety is everything.

    Sorry to be so serious, but these things scare the hell out of me.

    Only last Monday I had to visit a burnt out house where the owner died. It isn't nice. He fell asleep on the sofa with a lit cigarette.

    Structure is something else entirely, but that's just bricks and mortar.
  19. Have Fun

    Have Fun pfm Member

    For future ref

    Loft Conversions are a big PITA to do properly & the work involved is often underestimated

    One of the easier & quicker methods is to strip the roof structure complete & renew with either a cut roof or attic trusses
    this gives you control over the structure & the insulation (sound & thermal that you need)
    more problematic for terraced or semi-detached dwellings

    Advice will be required from a structural Engineer & Building Control & you may need Planning permission for dormer windows
  20. sean99

    sean99 pfm Member

    Agree. My office is in a finished attic with a dormer window. I have a climbing rope with knots every foot tied through a hole in one of the the 2"x8" roof timbers (there's a bit of unfinished timber protruding into the space) and a small hand axe in case I can't get the windows open so I could belt a hole in the roof (this in the US so roof is wooden boards with tar shingles, not tiled.

    I would never spend any significant time in the attic without a large window I could easily climb out of and a rope securely attached somewhere.

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