Monopitch Roof Framework...

[Mulberry View]

This is a general arrangement detail for my Car Port, the layout is not something I'm looking to go forward with exactly. Can anyone help with a bit of practical advice as I'm not overly experienced in timber framing.

 

 

The masonry is built, inner and outer leaves are level, as per the drawing. Next to go on are the 47x100 wall-plates (I've allowed 10-13mm bed). Does the masonry cavity need to be closed? If so, what with? Should I put a DPC under the wall-plates?

 

I don't think I need 50mm battens for the render boards and by reducing them to 25mm, I can centralise the on-end 250mx50 timbers a bit better on the wallplates. I plan to add noggins between them. I also plan to set the outer wall-plate in a bit to allow the render boards to skirt down over the wall-plates, as we clearly can't apply the render in the way shown.

 

Any help to prevent my further procrastination is gratefully received.

[Russell griffiths]

If render is your preferred finish why are you changing from brick to timber. 
wouldn’t it be more straightforward to continue up in a concrete block and render that. 
If you are happier in timber then

i w put a dpc on top of the wall, then a treated sole plate first, use this to span the cavity and close the cavity in one go. 
then ceiling joists on top of sole plate, put noggins between joists and then another sole plate on top of joists then stud wall up from there. 
you want an angled top plate, or a flat top plate then an angled trimmer to take the metal web roof timbers. 
 

that’s a shit drawing. 

[Russell griffiths]

You will also need a substantial way of keeping any moisture from behind the render board running backwards into the structure 

I would use a wide dpc from the top of the ceiling joists downwards to create a tray damp to deflect any moisture outwards. 

Edited Saturday at 12:42 by Russell griffiths

[Nickfromwales]

Adding the wood (TF) section does complicate this, seemingly unnecessarily.

 

Plates for ceiling rafters and roof rafters can be done quickly and simply to connect those. 

[Mulberry View]

1 hour ago, Russell griffiths said:

If render is your preferred finish why are you changing from brick to timber. 
wouldn’t it be more straightforward to continue up in a concrete block and render that. 
If you are happier in timber then

i w put a dpc on top of the wall, then a treated sole plate first, use this to span the cavity and close the cavity in one go. 
then ceiling joists on top of sole plate, put noggins between joists and then another sole plate on top of joists then stud wall up from there. 
you want an angled top plate, or a flat top plate then an angled trimmer to take the metal web roof timbers. 
 

that’s a shit drawing. 

 

Honestly, I hadn't considered it being anything other than timber, blocks would be so much easier. Just goes to show what it's like having your brain scrambled when you're a bit out of your depth!

 

What sort of blocks would be best for this?

 

And yes, the drawing is shit, its what we got from a £20k Architect. Makes me feel sick.

[Mulberry View]

1 hour ago, Russell griffiths said:

You will also need a substantial way of keeping any moisture from behind the render board running backwards into the structure 

I would use a wide dpc from the top of the ceiling joists downwards to create a tray damp to deflect any moisture outwards. 

 

How would this apply if I go for blocks?

[Nickfromwales]

8 minutes ago, Mulberry View said:

 

Honestly, I hadn't considered it being anything other than timber, blocks would be so much easier. Just goes to show what it's like having your brain scrambled when you're a bit out of your depth!

 

What sort of blocks would be best for this?

 

And yes, the drawing is shit, its what we got from a £20k Architect. Makes me feel sick.

Stick with us, kid   

[Mulberry View]

Just now, Nickfromwales said:

Stick with us, kid   

 

I am always grateful for the help on here, I couldn't have done this without. 😎

[Nickfromwales]

8 minutes ago, Mulberry View said:

 

How would this apply if I go for blocks?

A metal “bell” strip would be the junction between bricks and blocks, to kick the drip / rain away. Different types / sizes, so ask £20k boy to go draw something quick and simple; as if it was coming out of their pocket not yours for eg.  

[Mulberry View]

Just now, Nickfromwales said:

A metal “bell” strip would be the junction between bricks and blocks, to kick the drip / rain away. Different types / sizes, so ask £20k boy to go draw something quick and simple; as if it was coming out of their pocket not yours for eg.  

 

The £20k girl is history. That a blessing and a curse. I feel relieved to not have the arguments and arsehole'ish attitude, but we're left trying to figure out a lot of these weak details.

[Nickfromwales]

13 minutes ago, Mulberry View said:

 

The £20k girl is history. That a blessing and a curse. I feel relieved to not have the arguments and arsehole'ish attitude, but we're left trying to figure out a lot of these weak details.

It can prob be derived here, better, for free.
 

These pro’s are just annoyingly expensive and underwhelming. About to get another new clients architect placed into the nearest bin, which actually happens a lot when I’m involved and demonstrate the long list of faux-pas. 
 

Current clown hasn’t actually followed the approved planning application, so that chat I had with the client to highlight this last week was “enlightening” to say the least. Then that moved quickly to being infuriated.
 

Operation lead balloon was in full effect, yet again.

[Russell griffiths]

1 hour ago, Mulberry View said:

 

How would this apply if I go for blocks?

It wouldn’t as you would have a cavity all the way to the floor. 
and being an open carport I presume a bit of moisture will quickly dry out if there’s a bit of breeze to blow through it. 

[Oz07]

Take external skin right way up level with top of rafters, pro need to leave top course till rafters on so know where to set line. Take internal skin up and either sit rafters ontop or use a pole plate and hangers. If sitting rafters on blockwork probably need trimming to sit flat on the block and a bent strap hanging over end of blocks. Can you do this off your own back nowadays or do bcos want some kind of detail drawing

[Russell griffiths]

Remember if you take this up In block work you need to treat it like a gable wall. 
so angled ties at ceiling joists level, then more ties at rafter level. 
the ties stop the wall bowing out and restrain the ceiling and roof rafters, it all works together. 
 

with the icf walls you have done there wasn’t such a need as the structure is very rigid and stiff on its own, a block cavity wall can be a bit wobbly. 

[Mulberry View]

On 13/12/2025 at 15:46, Russell griffiths said:

Remember if you take this up In block work you need to treat it like a gable wall. 
so angled ties at ceiling joists level, then more test at rafter level. 
the ties stop the wall bowing out and restrain the ceiling and roof rafters, it all works together. 
 

with the icf walls you have done there wasn’t such a need as the structure is very rigid and stiff on its own, a block cavity wall can be a bit wobbly. 

 

Thanks @Russell griffiths

 

To make the rest of the structure work, I can see me using a timber ledger plate bolted to the blockwork for the ceiling joists to pick up on. They need to resist pull-out, so I imagine I'll be using a combination of nails and screws, along with nailing the tops of the hangers over onto the top of the ledger.

 

As for the wall-ties, I don't fully understand that, but will a brickie know what to do? Or is this just regular wall-ties as have been put in all the way up so far?

 

I'm pretty sure the roof on this will be EPDM, so I expect I'll lay an OSB deck on top of the Posis, oversailing onto a timber wall-plate with angle-packers on the top of the masonry. Does that all sound right?

[Nickfromwales]

3 minutes ago, Mulberry View said:

 

Thanks @Russell griffiths

 

To make the rest of the structure work, I can see me using a timber ledger plate bolted to the blockwork for the ceiling joists to pick up on. They need to resist pull-out, so I imagine I'll be using a combination of nails and screws, along with nailing the tops of the hangers over onto the top of the ledger.

 

As for the wall-ties, I don't fully understand that, but will a brickie know what to do? Or is this just regular wall-ties as have been put in all the way up so far?

 

I'm pretty sure the roof on this will be EPDM, so I expect I'll lay an OSB deck on top of the Posis, oversailing onto a timber wall-plate with angle-packers on the top of the masonry. Does that all sound right?

Just order the posis with a longer upper chord   Have that long enough to fly over the top of the wall so the OSB has something to fix down into.
 

Then fix the longer chords to the wall plate. This allows a bit more movement between structural elements vs the OSB trying to contend with the movement of the posis vs wall plate.

 

The edpm will heat up and cool down seasonally, expanding and contracting, so I’d consider creating some ‘give’ at that junction. 

[JohnMo]

19 minutes ago, Nickfromwales said:

Just order the posis with a longer upper chord

Yep, our longest over hang is about 4m.

 

Basically fixed to two wall plates.

 

Whole roof was engineered by posi supplier and approved by structural engineer. Each end of the house has a 6" steel pole anchored to a big block of concrete, as additional hold down

 

 

 

[Mulberry View]

3 hours ago, Nickfromwales said:

Just order the posis with a longer upper chord   Have that long enough to fly over the top of the wall so the OSB has something to fix down into.
 

Then fix the longer chords to the wall plate. This allows a bit more movement between structural elements vs the OSB trying to contend with the movement of the posis vs wall plate.

 

The edpm will heat up and cool down seasonally, expanding and contracting, so I’d consider creating some ‘give’ at that junction. 

 

OK, so masonry terminated flat, wall-plate added also flat, then Posi essentially top-chord hung on the outer wall-plate (with some angled wedges) and fixed down.

 

Where is the inner leaf brought up to? Built around the Posis or only to the underside if the Posis? Cavity closed?

 

Sorry for all the questions.

[Nickfromwales]

Cavity doesn’t really matter, it’s just about the wall profile here tbh. 
 

4 hours ago, Mulberry View said:

top-chord hung on the outer wall-plate (with some angled wedges) and fixed down.

If you do a mock up you can ask the posi gods to dress the ends for you to sit on flat. They add the wedges and away you go. “Plonk & play”. 
 

4 hours ago, Mulberry View said:

Where is the inner leaf brought up to? Built around the Posis or only to the underside if the Posis?

Wall plate sits across both, flat, and posis made to fit on as per the above.

 

4 hours ago, Mulberry View said:

Sorry for all the questions.

We accept your apology. Don’t do it again.