Support for Dormer

[frank999]

Hi,
Below is an image of my approved plans for a loft conversion, on the far right are details (or lack of) for the rear facing dormer wall, at the base of the wall (under the sole plate of the dormer is a rectangular box with a cross through it, no details on plans have been provided - should not this sit on top of the beam adjacent - or do I fill this void with some thing ??
Thanks

View media item 48354

 

[^woody^]

That designates a timber section - a massive timber section by the looks of things 150x300?

 

[RonnyRaygun]

The dormer wall is sitting on your external masonry wall isn't it? Presumably you will have a wall plate and studs making up the dormer wall. The voids will be filled with insulation?

 

[freddiemercurystwin]

I think you should add another steel!

 

[^woody^]

Was this one of chapeau's bargain basement architects?

 

[RonnyRaygun]

Why isn't the LH beam under the dormer wall? And why is the RH beam even required?

 

[freddiemercurystwin]

Maybe Polstar did it?

 

[RonnyRaygun]

That designates a timber section - a massive timber section by the looks of things 150x300?

Couple of solid oak railway sleepers required then

 

[frank999]

LOL - of course another steel - lets push out the boat.

Interpreting the drawings, yes its huge lump of timber, but obviously thats not the case.

What is it ??

Beneath this are two openings in the rear wall, a bedroom window and bathroom window - i am going to fit windows of the same size so the support posts (7x 100x100mm specified) built into the dormer wall will rest either side of the openings and the existing lintels, any load from the flat roof will transfer to the header (2x 50x100mm timbers) then onto the posts, sole plate and down onto the wall.

Why would my architect draw such a anomalous detail in, the dormer posts and studding will I assume come off of a wall plate 50x100mm sat on mortar on the masonary wall - as suggested by Mr Raygun.

I assume the steel is set back, so it can sit centre on the 330mm padstones - which themselves look set back from the rear wall along the flank walls by 150mm +

 

[^woody^]

Interpreting the drawings, yes its huge lump of timber, but obviously thats not the case.

Joking aside, that is the case.

It's denoted as a timber section, and it's not a clear mistake - as it is perfectly feasible (although impractical) for it to be a timber

We could guess all day, but there is only one person who knows what it is supposed to be - your illiterate designer

I love the way he bothers to draw three little circles for bolts, and those stupid things on the steel beams/joists but fails to include anything remotely useful

 

[RonnyRaygun]

You need to build a stud wall. Provided the lintels below are sufficiently robust, I can't see why you shouldn't just use short sections of timber at 400mm centres.

If you want to use a single timber as shown, get six 50x150s and bolt them together

 

[frank999]

The railway sleepers seem like a top idea ! wonder if they come as C24 strength.

This diagram is from the Structural Engineer.

The structural engineer has got me shot bolting restraint straps onto the flange of the steels - yes, nice of him to draw me guides for the 4x nailing points very helpful.

Come to think about it, the 3 dots cant be bolts surely, that would require just one bolt with a toothed connector ?

Seriously - that 'block' shouldn't be there surely ?

I'm waiting for a call back - another one thats never made.

 

[frank999]

Mr Raygun, thanks, thats what I thought should be done - but whats the point, you've got two sole plates then, unnecessary in my opinion

 

[RonnyRaygun]

The railway sleepers seem like a top idea ! wonder if they come as C24 strength.

D30 or D40 strength more like!

 

[^woody^]

I'd be inclined to make it as a box beam, but it all depends on the length. It may well be that the new timber wall can be taken down to the house wall.

I'm not sure what the 1st beam is doing though if you have a wall next to it to sit the new joists on? And will it actually fit under any rafters - judging by the drawing it wont if there are any rafters on the side of the dormer