We’re having plans done for a loft conversion on top of our 3-bed mid-terrace.

As the loft ceilings will be really low (2m) and our 1st floor ceilings are really high (2.9m), the guy doing the plans suggested lowering the ceilings.

Makes sense, however his very tentative guess at the added cost for this was around 50k.

That seems excessive to me, obviously got no real clue though.
Another builder last year quoted us 55k +vat for the entire conversion including plans (without ceiling lowering).

Does it sound reasonable? How much is it likely to add to the total cost to lower the ceilings?
Anyone have experience of this? Or is a builder ? 🙂

Whats the age/style of property?
Do you mean first floor ceilings or ground floor ceilings?

First floor ceilings (loft floor) will likely need replacing or heavily strengthening anyway, so shouldnt be too much more work or materials to drop them.
If youve got some spindly timber trusses currently forming the attic floor and rafters (last 50 years build) then almost certainly you will need a new floor and supporting structure for the rafters.

If you mean ground floor ceiling, and therefore lowering the first floor, again, depends on how the floor joists are currently attached to the walls. This is going to need replumbing any upstiars bathrooms, and the stairs will need redoing too.

Sounds like moving may be easier!

Surprised that 2m is a building regs accepted ceiling height for a (liveable) loft conversion – unless it’s being done as ‘storage space’!

As for lowering ceilings – you’re not just lowering the joists – there’s the electrics to move, possible plumbing to moves, walls to shorten, replastering of rooms below, redecorating rooms below. Ball-ache of a job.

Mid-terrace from around 1910, first floor ceilings. Good point about the strength anyway cos I think they are just spindly things up there for the floor currently… makes his guess seem even more excessive!

Mid-terrace from around 1910,

theres 2 real options for the loft conversion, depending on whether you have purlins spanning the full width supporting the roof rafters, or if they are currently propped off the attic floor/internal walls.

Ideally we’d get the roof fully supported on the party walls (and front and back walls) only, leaving the new stronger (which usually means deeper) floor to sit on the internal load bearing wall (assuming its brick, based on the age). This means reducing the height of the brick wall(s), and any electrics, and replastering the ceiling. I cant see the extra 50k.

Another builder last year quoted us.. for the entire conversion including plans

These all in one builder type arrangements* rely on doing something simple a lot of times (if you’re in a town/area where a lot of the houses are similar), you may have scared them by asking for something outside their comfort zone and they;ve given a high quote to discourage it.

*nature of my job means I only see these when theyve cocked them up, so I am probably guilty of tarring them all with the same brush based on a few poorly thought through examples.

We do have the massive purlins resting on the party walls. Yes all walls are brick.
The party walls are actually just a single row of bricks for part of the house, which might complicate matters!

At the moment we’ve got an architectural technologist doing the plans and no builders are involved yet.

Next door neighbour to us did this (Edwardian 3 storey terrace) mucho pain in the arse for all concerned – make sure you do get party wall agreements in place & watertight if you go ahead.

We do have the massive purlins resting on the party walls. Yes all walls are brick.
The party walls are actually just a single row of bricks for part of the house, which might complicate matters!

Sounds like the roof will take care of itself then. Lots of hassle saved there.

if youve got suitable side to side brick walls below for the new/strengthened floor to go on, and can do something clever with trimming the stiars, you may be able to get away wihtout doing anything to the party walls.

Probably cheaper to just raise the roof. That’s our plan, we don’t have enough attic height for a conversion, so will need to raise the roof 18in or so…..

When we did it (years ago) we weren’t allowed to raise the roofline. We just squeaked in with the required clearance (2m I seem to recall) by dropping the new steel supports for the loft floor between the existing wooden beams for the first floor ceiling. Cost more in steel (thicker squarer beams) but meant that the conversion was doable.

Your not just allowed to raise the roof, especially if it is being done under permit development, which it most likely is. Council will not sign it off if you try it on.

I’ve done several loft conversions were we have lowered th 1st floor ceilings to gain extra height in the loft, 50k is a ridiculous figure.
Mid terrace house, you’ll only be allowed a maximum of 40 cubic metres additional loft space, so given that, your floor/ceiling area will be relatively small, presumably you have 3 bedrooms(1 being a small box room) and bathroom on the existing first floor?

If you have a standard roof construction with rafters and purlins, sounds like you do. The roof will take care of itself in the build when you flip it up to make the dormer, no more extra work required there to lower the ceilings or strengthen the pitched side-it will be done the same regardless

You will most likely get away with keeping the actual 1st floor ceiling height the same in the end.
The small Ceiling joists (likely 100mm deep) will be taken out, the steels dropped in their place, bottom of steel at the same height as existing ceiling joists, beams likely to be 203mm x 203mm and then new bigger floor joists fitted in between the Web of the steel.

Normal quick loft conversions would Install the steels above the existing floor joists with a minimum of 25mm gap between top of ceiling and bottom of steel beams so as not to push any weight down on to 1st floor ceilings.
That means
25mm gap
203mm steel
22mm chipboard floor covering
= 250mm headroom saved if you remove 1st floor ceiling h joists and replace with steels for loft.

Does that make sense?!

At the moment we’ve got an architectural technologist doing the plans and no builders are involved yet.

Based on the costs he’s throwing about probably want to get a second opinion.

Possibly from someone who knows .

That means
25mm gap
203mm steel
22mm chipboard floor covering
= 250mm headroom saved if you remove 1st floor ceiling h joists and replace with steels for loft.

I’m obviously missing something, but surely you’re only saving 100mm (old joist height) plust 25mm (gap) by removing the old joists – it seems the 203mm steel and the 22mm chipboard is there either way?

Yes sorry 5lab, I got my figures wrong, you’ll likely save around 150mm doing that as old plaster is alot thicker than new plasterboard, my mistake.

Ok I spoke to plan guy again and got some things cleared up, seems I misunderstood him slightly – he didn’t mean 50k extra to lower the ceilings in this case, rather he was referring to the cost for the whole job of lowering ceilings by itself (I think). Based off another job he’s doing where they’re just lowering ceilings for some reason.

As for more precise costs for this job, it really depends on if the internal wall is load bearing, the structural engineer’s getting involved later this week so we’ll have a better idea then.

As they’re going to be poking holes in our already battered-looking crumbly plaster ceiling anyway, I like the idea of lowering them and getting the job done properly… just not at 50k!

Raising the roof not really an option. Don’t think we’d get permission anyway.