Loft height - lower ceiling or not >> your opinion ?

[aroundM21]

Hello world ....

An architect has drawn up plans for my loft conversion. I now have 2 choices :

1) lower the ceiling of the 1st floor so that the loft is a good height - we'd gain at least 5 inches so it would be 6'5.
2) not lower the ceiling and have a loft exactly (within 5 millimetres) 6 foot high.

The room would be approx 9ft x 11ft in area. Our main use would be as a childs bedroom (child - not teenager, yet) but obviously we also want an investment that will hold-up in a future sale.

I'm concerned about the disruption / re-decoration required if we lowered the ceiling.

I'd be most interested to hear from people who have done something similar to either of my 2 options, and how they feel about it with hindsight ....

Of course builders quotes may make the decision but the Architect felt lowering the ceiling is not many more days effort than laying new floor joists closer together.

Thanks in advance ......

Mike (Manchester).

 

[Shytalkz]

You've answered your own question: there is much more disruption, if you start messing around with the ex ceiling. Try living in the rooms directly underneath, for a start, while this is going on!

Far better to get the SE to look at the following options:

• wider, shallower joists;
  wider, shallower joists at closer centres;
  increasing the stress grade of the timber;
  using a ply deck in conjuction with joists to cut the overall depth down;
  changing the structural arrangement to reduce spans, if possible.

 

[buryboy]

Hi there

Can't help with the original question , but my loft is due to start in a few weeks and would have loved a bit of extra height - I never questioned the architect over the width vs height of the new joists , I just assumed they were standard size for the job.

They are in at 2" by 9" at 40cm centres. Now it would have been a big help to have say 3" by 7" instead, an extra 5cm would come in handy .

I presume now that the plans are all passed there is nothing than can be done , or is it feasible to ask the planners / building regs people whether a swap could be made ??

Thanks
Graham

 

[Shytalkz]

You can change it. Just get the designer to look at alternative joist sizes for you. Then submit the calcs to the BCO as an amendment to the approved details.

 

[buryboy]

Thanks Shytalkz

Having had to do a search to find out what a BCO is , I have a couple of questions.

1) Is this a formal re-application that will take a few weeks to come back ? - as my builder could be starting in as little as a fortnight. Will it cost me anything bearing in mind that my plans have already had one formal revision ( as the fall on the dormers was originally submitted with a steeper slope than I wanted ) ?

2) I actually think that having looked at it again , there will be little benefit because there are 3 steels , one under each dormer at 254 by 254 , and one down the centre at 203 by 203 , so I guess that I would, to get any real benefit , also have to have the steels re-sized which I am not sure is a) possible or b) practical in the timescale

Would still be interesting to know the outcome should I have to go through this kind of thing in the future

Graham

 

[Shytalkz]

Sounds like the steels snooker your ambitions then! The 254s sound a tad heavy, unless you've got humongous spans and/or loadings. At best, with some jiggery-pokery the 203 might come down to a 152x152 section, but again that depends on spans and loadings on the beam. If the beams are running across the existing joists, then you can shave a couple of inches off by cutting the joists at the beam position and lowering them down to 10mm or so above the existing ceiling. That's more work, obviously, but will gain you that couple of inches without any redesign.

However, if you decide to go for a revision, there is no charge from the LABC and you're under no obligation to wait for formal approval (although proceeding before approval will be at your risk), it's just a revision; obviously there will be fees from the structural designer though.

 

[buryboy]

Thanks again shytalkz

The steels run perpendicular to the existing beams. The builder intends to put the steels a centimetre or so above the top of the existing joists ( though originally I thought they were going to be cut into the joists though I understand by doing this , the house would fall down unless I spent a few grand on acros / new ceilings ) and the new joists will then effectively sit on top of ( or just above) the existing joists.

If I'm understanding you correctly , cutting into the existing joists to say 10mm , surely this will weaken the structure almost as much as cutting through them ?

..but if the existing joists could be cut into . presumably the new joists would then be strapped to the side of the existing joists to take advantage of the new lower steel level ?


Thanks again for your help , most appreciated
Graham

 

[Shytalkz]

It - as in the whole structure - won't fall down, although the ceiling will need propping. The concern in the short-term is the removal of the tying action of the joists to stop eaves spread, but props under the existing purlins as well will alleviate this.

If the beam is cut in, the existing joists are then nailed to the side of the new ones, which then act as ties by virtue of being fixed to the steels; a BAT strap every third old joist where these are cut will provide a mechanical connection from one side of the roof to the other. Job's a goodun.