Do i need RSJ for lowering the ceiling?

[davidmadona80]

Hi Esteemed experts,

I had previously posted here for advice on removing the wall between front and rear rooms in a terraced house downstairs to make bigger living area. The advice was to put a RSJ beam downstairs to support the single brick wall which run all the way to celing supporting the Joist and finish there. Loft is clear.

I now want to lower the ceiling & board it to make a bigger storage space in the loft / for future loft conversion to avoid going through same hassle again. I am going to remove the old ceiling.

Until now i was thinking i would put another RSJ on first floor to support the lowered ceiling, but yesterday my architect said you can rest your joist on the single wall without having to put another RSJ. He said he can make sure the RSJ downstairs is big enough to support this.

This sounds brilliant idea to me if it can be done, as it would save me money and hassle putting second RSJ if it can be done by extra strong single one RSJ downstairs.

I just thought i would get some advice here, can you please suggest if this can be possible, i would appreciate as the work is scheduled in 2 weeks time.

Thanks a lot.

illustration here to give idea.
View media item 76567

 

[ban-all-sheds]

my architect said you can rest your joist on the single wall without having to put another RSJ. He said he can make sure the RSJ downstairs is big enough to support this.

Did he say that you would then not need any more structural work done to allow a loft conversion?

 

[davidmadona80]

my architect said you can rest your joist on the single wall without having to put another RSJ. He said he can make sure the RSJ downstairs is big enough to support this.

Did he say that you would then not need any more structural work done to allow a loft conversion?

Yes he said there would be no additional structural changes required or the RSJ. I can use the existing wall where joist are resting but a bit lower. The downstaris RSJ would be calculates to support the wall as well as ceiling.

 

[tony1851]

Unless your architect has seen the roof structure before giving you that advice, he is a nit.

In many cases, the ceiling joists also prevent spreading of the outer walls.
Once the ceiling joists are out, there is the possibility that the rafters push out on the tops of the walls.

Lowering a ceiling to put in a loft conversion is perfectly feasible, but the existing rafters will have to be restrained in some way.

Is this an older-type terrace house?

 

[davidmadona80]

Yes , this is a 1900 terraced house. The architect Has not seen the loft. What if i put the lowered celing first and then remove the old ceiling, would that help much ?

 

[tony1851]

It makes no difference. The ceiling joists in those old houses are often nailed to the wall plate, which in turn supprts the rafters. Once the ceiling joists are out, there is nothing to stop the rafters from pushing out the top of the wall.
It doesn't happen overnight, but it will gradually.

If you are putting joists in at a lower level (for a future floor?). you need to find some way of tying the rafters back to your new joists, to stop them spreading. This shows one way in an old terrace house;

Untitled

• tony1851
• 27 Apr 2014
• 2

 

[davidmadona80]

This shows one way in an old terrace house

.

Thanks Tony, you have made a really good point which i never thought of. After looking at your picture, i thought to go up and check hows it in my loft.

After having a look ( a pic attached) I can see a big wooden beam supporting the rafters, is it possible to use that beam to reinforce the hold on the rafters by nails or extra wood to hold them and avoid extra support from ceiling ? or would it be not appropriate place to support the rafters? (highlighted with arrow)

View media item 76643

 

[davidmadona80]

Hello again, would the above be enough to support and hold the rafters ? or would i need something at wall plate ? thanks

 

[tony1851]

It's not a case of supporting the rafters but of tying them back to make sure they don't push out on the top of the wall.

There are several ways: one is to fix pieces of timber to each one (as low down the rafter as possible) and fit the other ends of these timbers to your new (lower) joists, as in the pic.

Another way is to fit gussets of plywood, to connect each rafter to a corresponding joist, with a rigid joint.

 

[davidmadona80]

Thanks Tony, I will keep that in mind.

Another question :

I want to do this as a DIY project, what sort of tools would I need if you can recommend ? I believe its ll be drills, spirit levels, shaw ? any major tools i might be missing ? thanks

 

[davidmadona80]

Thanks Tony, I will keep that in mind.

Another question :

I want to do this as a DIY project, what sort of tools would I need if you can recommend ? I believe its ll be drills, spirit levels, shaw ? any major tools i might be missing ? thanks

 

[ban-all-sheds]

I have to say that if you don't already own, know how to use, and when and where, the tools for this job you are probably not yet a sufficiently experienced DIYer to be tackling this job.

 

[davidmadona80]

I have to say that if you don't already own, know how to use, and when and where, the tools for this job you are probably not yet a sufficiently experienced DIYer to be tackling this job.

I own the above with more general DIY tools, i meant any specialist tool i might be missing ?