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Home Loft Wall in old terrace

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 raussmf 06 Jan 2021

Hi there,

I know the clear answer is to ask a structural engineer but I dont really have the funds / time to do that sadly.

I live in a standard 100 year old terrace house in the North West of england and was wondering if anyone has experience of putting a small wall in the loft?

Its currently not boarded and has trusses supporting the ceiling with a layer of insulation on top.

As a start I was think of adding 2x4" braces at 600mm centres perpendicular to the existing trusses, add smaller legs, replacing insulation (to 270mm depth) then placing boards on top.

Can anyone comment if this sounds strong enough to support the occasional fall onto a matt without crakcing the plaster below?

Hoping theres loads of these walls in manc and sheffield already!

Post edited at 14:59
 Marek 06 Jan 2021
In reply to raussmf:

Can't help with the structural question, but you might want to think about dust. Old insulation is likely to be fibreglass. The loft is likely full of fibreglass (and other) dust which you really don't want to be breathing. Solution? Don't know - perhaps it can get cleaned out? Seems non-trivial.

 raussmf 06 Jan 2021
In reply to Marek:

Valid point I hadn't considered - fibreglass needs to be boxed in so would need to board the walls as well and then give is a very good hoover. Or buy insulation board but would rather not.

Thanks for that

In reply to raussmf:

The first thing to check is how big the joists are. Quite a lot of lofts have joists that are just thick enough to be ceiling joists for the rooms below. While you can walk on them, repeatedly falling on them is not the greatest thing in the world.

 chris_r 06 Jan 2021
In reply to raussmf:

Any chance your 100 year old terrace has a cellar? Landing on solid floors is a lot less impact on a house than landing on loft joists.

Sorry, I know this is a typical UKC answer - not answering the question you've asked!

In reply to raussmf:

I don't quite understand but it sounds very dodgy.  When you say trusses, do you mean joists? If so they wont be strong enough to act as a floor. Adding members between them won't help significantly.  Regardless, when you come to sell you would have problems if it hasn't been properly designed.  Do it properly or not at all.

 raussmf 06 Jan 2021
In reply to MG:

Yep I mean joists.

Fair point there is a big difference between creating a room and creating a storage space. A lot of the online info is for creating storage spaces not a habitbal space.

I may go up again this evening to investigate further.

 raussmf 06 Jan 2021
In reply to chris_r:

Sadly not!

 jkarran 06 Jan 2021
In reply to raussmf:

Attics seem like such a horrible place for a training wall but they are huge unused spaces.

Before you go too far with your plans you'll need to work out what length of timber you can get round all the corners in your house (including through the hatch) and what size boards. Try one before you buy a pallet. Also where the underlying support is (the interior walls).

You could stiffen the ceiling joists by gluing and screwing timber to them (adding depth) and making sure any (butt or better if you can, scarf) joins in the new timbers lie above supporting walls but you'll probably still find old plaster lets go eventually if you're jumping about on it.

I'd suspend a new floor above the ceiling and decoupled from it, feed the load as directly as practical into walls below. It doesn't need to be super stiff but you should give some thought to future owners who'll almost certainly use it for storage and to what will happen when any structural screws rust if the floor ends up not bearing directly onto the walls. If for example the ceiling joists are 3" deep you could put 5" joists between them, with 1" of isolation from the joist to the ceiling and only 3" of built up thickness. Plenty of room for insulation in that. Also make sure the air trapped between the new floor and ceiling below has plenty of freedom to escape or they'll end up coupled together by air pressure anyway as you flex the new floor.


 Mark Edwards 06 Jan 2021
In reply to jkarran:

Exactly what I was thinking before I got to your post. It doesn’t take a lot to crack plaster.

Although I wonder if sending the shock force into the walls is a good idea. A 100 year old house is probably mortar not concrete. My 1890’s house stands up but if you want to take apart a wall you can pull it apart by hand once you have made a hole. If you are going to have a decoupled floor then maybe its best attach the floating floor to the (wooden, flexible) roof trusses instead of a strong but fragile old wall.

 AJM79 06 Jan 2021
In reply to raussmf:

Don't listen to anyone who says to "support your floor as directly as possible into walls below". Any new floor needs to be 100% supported by masonry. Do not screw a new floor into anything timber, if you need to fit a bearer then this should be bolted to masonry (but as you'll be at the top of the wall this will probably be unsuitable. Your only real chance of adding new flooring joists would be to knock off the top course or two on the inner leaf of your external walls and feed new, larger joists over the span - sitting 100mm over the masonry at both ends. This is impossible without lifting a section of your roof to feed the joists in unless you have a spine wall in the center of your house which you can use to break the span (many terraces do but they normally only support the staircase and usually end on the first floor). The other option you might have is of creating one joist for the span by bolting two timbers together - this is definitely one for a structural engineer though. If you need to find out what size joist you need for the span then look to building regs (you should be able to find a chart online) and you can keep the depth down by using a greater width (i.e 3" instead of 2") or a greater strength grade (i.e C24 over C16). As other posters have mentioned leave a gap between the plastered ceiling and the base of your new joists to avoid any crackage and if you need to shim any joists then a couple of slates smashed up normally do a good job. If you do fit new joists then make sure to build your masonry back up to fill in around your joists, this will prevent any future twisting. If you're not sure then don't do it, a bad floor can fail and may harm anyone below not just you, aside from costing a small fortune to fix. 

 MischaHY 07 Jan 2021
In reply to raussmf:

To be honest fella the real answer is to build yourself a freestanding board in the living room or similar. You can always make it retractable or folding. Alternatively a great solution I've seen done is a purpose built board shed in the garden. 

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