Corner Window Lintel?

[Joe87]

Hi all, Im almost done on the construction of a garden room, im close to getting to the roof part of the build. Ill be having a corner window, but am unsure what to use to span the gap at the top?

I was thinking of having a load bearing corner post, which a window friend has said he can get hold off, and spanning the wall plate across to the corner post and then to the other wall.

 

Will this be enough for part of the warm roof to go on top? I was thinking a 100 x 50 wall plate, but should i double this up above the corner window for more strength for the roof beams to go onto?

 

Thanks for any advice.

 

Cheers

 

Joe

[tonyshouse]

Need calcs, I would not use wall plate or doubled up wall plate . Depending on direction of joists I would use 150 x100. But may as well use a beam same size as roof joists 

 

if roof only sits on shorter span 100x100 might just do it 

 

 

[Joe87]

10 hours ago, tonyshouse said:

Need calcs, I would not use wall plate or doubled up wall plate . Depending on direction of joists I would use 150 x100. But may as well use a beam same size as roof joists 

 

if roof only sits on shorter span 100x100 might just do it 

 

 

Thanks for the info, a little more information that I should of added before. 

 

The gap in the corner is about 1 meter 30 on the front and 2 meters on the side, to the corner post.

 

The joists will be going from the back of the building to the front, so the joist ends will rest on the 1.3 meter section. The joists are quite a slab. I'll be using 9x2 at 6 meter lengths to span the gap. 

 

Not to sure if that all makes a difference on what I should use. 

 

Cheers. 

[markc]

15 minutes ago, Joe87 said:

Thanks for the info, a little more information that I should of added before. 

 

The gap in the corner is about 1 meter 30 on the front and 2 meters on the side, to the corner post.

 

The joists will be going from the back of the building to the front, so the joist ends will rest on the 1.3 meter section. The joists are quite a slab. I'll be using 9x2 at 6 meter lengths to span the gap. 

 

Not to sure if that all makes a difference on what I should use. 

 

Cheers. 

If you are using 9x2 joists, I would use the same as a front and rear beam with joist hangers. ( as opposed to sitting the joists onto a wall plate) You wouldnt need the post as the corner would be supported by the front member (sitting on the front wall) and the end joist (sitting on the end wall)

[Joe87]

2 hours ago, markc said:

If you are using 9x2 joists, I would use the same as a front and rear beam with joist hangers. ( as opposed to sitting the joists onto a wall plate) You wouldnt need the post as the corner would be supported by the front member (sitting on the front wall) and the end joist (sitting on the end wall)

 

 

Hi Mark, 

Is the image I found online sort of what you're suggesting? So I would have the 9x2 along the whole of the front and back wall and hang my joists from that or just for the corner? Sorry to be a pain 

 

[markc]

@Joe87 yes thats the idea.. Turn the whole roof into a box structure 

[Joe87]

6 minutes ago, markc said:

@Joe87 yes thats the idea.. Turn the whole roof into a box structure 

Brilliant OK, this may actually make life easier for me as a whole because I have a steel beam to contend with aswell so I can use this through that aswell on the inside. Thanks, much appreciated. I probably won't need the corner post either which would be amazing. 

[Mr Punter]

I think there is a rule of thumb that the cantilever length should be less than 1/3 of the supported section.

[Joe87]

29 minutes ago, Mr Punter said:

I think there is a rule of thumb that the cantilever length should be less than 1/3 of the supported section.

Thanks for the info. So a 6 meter beam should be just on the dot then for a 1/3 overhang. 

 

Maybe a stupid question but if I used a ledger board, does it go along the top of the wall and attach to the masonry with bolts? Then I would use hangers on the ledger board for the joists? Then obviously this ledger board would span the corner gap, is that correct? 

[markc]

4 minutes ago, Joe87 said:

Thanks for the info. So a 6 meter beam should be just on the dot then for a 1/3 overhang. 

 

Maybe a stupid question but if I used a ledger board, does it go along the top of the wall and attach to the masonry with bolts? Then I would use hangers on the ledger board for the joists? Then obviously this ledger board would span the corner gap, is that correct? 

In a manner of speaking es, but to make things easier/simpler/cheaper - build the box structure as a unit sitting on the walls, use either joist hangers or screw straight through as you have no access problems. Then when its all fixed and levelled (if necessary) use straps to secure the whole thing down to the walls

[Mr Punter]

Carefully mark out the rim board and pre-drill clearance holes for the joist locations before you lift it up.  Staple DPC to the bottom edge of the rim board.  If the rim board lines up with the outside edge of the blockwork you will have 50mm to rest the joists.  Fix the joists with some of these https://www.screwfix.com/p/turbocoach-coach-screws-yellow-zinc-plated-8-x-100mm-250-pack/8533x

[Joe87]

4 hours ago, Mr Punter said:

Carefully mark out the rim board and pre-drill clearance holes for the joist locations before you lift it up.  Staple DPC to the bottom edge of the rim board.  If the rim board lines up with the outside edge of the blockwork you will have 50mm to rest the joists.  Fix the joists with some of these https://www.screwfix.com/p/turbocoach-coach-screws-yellow-zinc-plated-8-x-100mm-250-pack/8533x

 

Thanks again. I do have just a few more questions. Sorry to keep on!

Just so I'm totally clear on what you're both saying. 

 

1. Using the screws you've suggested Mr punter, do I screw from the outside of the rim board through into the end of the joist. If so how many screws? Or should I skew nail the joist into the rim board inside, like you would a wall plate? 

 

2. How would I level the rim board, would this be done with mortar the same as a wall plate would to get the level?

 

3. If I did decide to still use wall straps to anchor the roof down, how would I get them to run down the inside wall with the rim board on the outside edge of the block work? Could they be bent into position or is there something else on the market for this type of thing? I'm unsure otherwise how the whole thing would be secured to the actual building structure. 

 

Just one more I promise, haha. 

 

4. To get an overhang of 30cm or so around the front and side that is showing, can I screw some noggins on to the rim board outside face? So I have a place for downlights etc and is it OK to use cut offs from the 9x2 joists for this purpose. 

 

Thanks guys. I do really appreciate your help. Sorry for the questions but this is not originally how I was going to do the roof so I just want to make sure I have my head around it properly. 

 

Thanks again. 

5 hours ago, markc said:

In a manner of speaking es, but to make things easier/simpler/cheaper - build the box structure as a unit sitting on the walls, use either joist hangers or screw straight through as you have no access problems. Then when its all fixed and levelled (if necessary) use straps to secure the whole thing down to the walls

 

[Mr Punter]

1 hour ago, Joe87 said:

1. Using the screws you've suggested Mr punter, do I screw from the outside of the rim board through into the end of the joist. If so how many screws? Or should I skew nail the joist into the rim board inside, like you would a wall plate? 

 

Yes screw from the outside 3 each end.

 

1 hour ago, Joe87 said:

2. How would I level the rim board, would this be done with mortar the same as a wall plate would to get the level?

 

You can level this with packers.  If you really want to you can use mortar later to fill any gap.  I assumed that insulation etc did not matter as this is more like a shed / garage.

 

2 hours ago, Joe87 said:

3. If I did decide to still use wall straps to anchor the roof down, how would I get them to run down the inside wall with the rim board on the outside edge of the block work? Could they be bent into position or is there something else on the market for this type of thing? I'm unsure otherwise how the whole thing would be secured to the actual building structure. 

 

Can you run them down the outside?  Use stainless ones?  Def need straps.  If you want them inside you can use galv and fix a timber noggin to the rim board to make up the 50mm ish and fix to that. 

[Joe87]

9 hours ago, Mr Punter said:

 

Yes screw from the outside 3 each end.

 

 

You can level this with packers.  If you really want to you can use mortar later to fill any gap.  I assumed that insulation etc did not matter as this is more like a shed / garage.

 

 

Can you run them down the outside?  Use stainless ones?  Def need straps.  If you want them inside you can use galv and fix a timber noggin to the rim board to make up the 50mm ish and fix to that. 

 

Thanks mate! It's more going to be a garden room, I'll be putting a warm roof on top. I just couldn't figure out the corner over the window but you guys have really cleared it all up in my head. Thanks for all your help! I feel confident now I know what I'll be doing. Much appreciated.