Building control drawings

[nwnw]

I'm doing all the building control drawings myself, mostly in Sketchup.  These will be backed up by 'mark-up' details and structural report by the structural engineer.

I have a couple of examples of building control drawings to reference, but I could really do with more.

 

Is anyone willing to share their drawings with me?  Especially those covering a timber frame extension!

 

Once nearly done (about 75% there just now) and once complete I'll stick my drawings up here for you all to rip apart! 🙂

---------------

Edit: I meant to say, if you'd rather not put up in public then feel free to DM me.  Thx

Edited November 7 by nwnw

[ETC]

Post your drawings and I will have a look.

[Gus Potter]

10 hours ago, nwnw said:

Is anyone willing to share their drawings with me?

No, because I feel if you want to save money then you need to put in the leg work first, there is no free lunch. 

 

Your starting point is to learn how you put together a timber frame, how the lateral stability system works and so on.

 

If you make a good go at your TFand post your drawings  then I may chip in as an SE / designer  to give you some tips etc.. but I'm not going to share my intellectual property with you until I'm sure you have done the leg work.

 

 

 

[nwnw]

Ok, fair enough.  Not complete and meeting with structural engineer tomorrow, but here we go...attached are some of the drawings as they stand.

I'm based in North East Scotland so Scottish Building Standards apply.

I'll post some images too for reference.

Existing sunroom...

New structure...

If anyone wants to see any specific areas then just ask.

Oh, and please not that the steel has been reduced in size slightly so the flat roof timber looks like it's floating 50mm above it.  I'm not updating the structure yet as engineer might change things anyway.

 

All comments welcome!!

 

<<Moderator Edit: The previously attached drawings have been removed and they will be reposted further down the thread.>>

 

 

[nwnw]

New open plan space, utility to right and cloakroom/entrance top left.

[nwnw]

On 08/11/2025 at 00:27, Gus Potter said:

No, because I feel if you want to save money then you need to put in the leg work first, there is no free lunch. 

 

Your starting point is to learn how you put together a timber frame, how the lateral stability system works and so on.

 

If you make a good go at your TFand post your drawings  then I may chip in as an SE / designer  to give you some tips etc.. but I'm not going to share my intellectual property with you until I'm sure you have done the leg work.

@Gus Potter Hopefully you can see that I have 'done the legwork'.  🙂  

For me it's as much about having ownership as saving money.  I'm an engineer to trade so I have a good handle on loads & forces and can do all the calculations (although I'm engaging a structural eng to make the approvals process smoother).  But with regards the drawings, I want to make sure I get all the info on there that the BCO will be expecting.

 

[Mr Punter]

A few small points:

 

Maybe look at a fire resistant membrane on the walls.

 

The box gutter may fail at some stage and possibly rot out the walls.

 

The Kingspan phenolic insulation is good (better insulation and fire rating) but expensive.

[nwnw]

On 10/11/2025 at 10:06, Mr Punter said:

A few small points:

 

Maybe look at a fire resistant membrane on the walls.

 

The box gutter may fail at some stage and possibly rot out the walls.

 

The Kingspan phenolic insulation is good (better insulation and fire rating) but expensive.

Thanks for the feedback.

Any suggestions for membrane and I can have a look?

I'd like, if possible, not to have ugly guttering round the front of the cladding.  Any other ways round this?  My assumption was that EPDM would be pretty bomb-proof if done by a professional outfit, given the amount of flat-roofs done like this.

[markc]

Gutter on outside of the envelope and then cladding in front with access to downpipes if needed (removable cladding section etc).

haven’t read rest of post/s so might be barking up the wrong tree

Edited Tuesday at 11:19 by markc

[nwnw]

On 11/11/2025 at 11:17, markc said:

Gutter on outside of the envelope and then cladding in front with access to downpipes if needed (removable cladding section etc).

haven’t read rest of post/s so might be barking up the wrong tree

I sort of get the gist, but do you have any examples or x-sections of how this could be achieved?

[Russdl]

On 11/11/2025 at 11:04, nwnw said:

My assumption was that EPDM would be pretty bomb-proof if done by a professional outfit,

I would say it’s pretty bomb-proof if you do it yourself, it’s very easy and you’re more likely to take greater care than most pro’s. 

[Roger440]

Sketch-up! You must have the patience of a saint.

[Russdl]

2 hours ago, Roger440 said:

Sketch-up! You must have the patience of a saint.

When you get it. You get it. It’s brilliant. 

[nwnw]

One kind person pointed out that I had some personal details on the drawings posted so I have redacted and re-attached...

Layout - Proposed - Rev2.pdfElevations - Proposed - Rev1.pdfBuilding Control Report - redacted.pdfDetail02 - Roof - Rev2.pdfDetail01-Wall - Rev3.pdf

 

I've also made a few changes.  Structural engineer recommended going with a beam under the existing roof joists to keep the build simpler and cheaper.  After chatting through and thinking of the implications of the old timbers being varying lengths and sizes I've grudgingly agreed and changed the design.  Means I have a boxed in steel in the middle of the room but after modelling it doesn't look as bad as I expected.

He also suggested landing the beam on the stonework and underpinning, rather than 'goalpost' steel supports and pads.

 

[nwnw]

13 hours ago, Russdl said:

When you get it. You get it. It’s brilliant. 

Indeed.  I was frustrated with Sketchup for years then I took some time to learn to use it properly.

Once I started to group features, make components and use tags (layers) all my problems disappeared (problems:  usually dragging features by mistake and noticing 2 days later after everything was totally messed up).

[Spinny]

Some random thoughts...

Where will the TV go ? 

Where will kitchen and utility extractors go ?

Outside tap and powerpoint ?

Consider creating a lighting plan now so you can avoid lights clashing with ceiling joists or steel etc

Consider the potential for rain noise from the flat roof - was an unexpected issue for us using single ply PVC membrane - perhaps EPDM is better for noise - acoustic insulation ?

Pity about the beam.

That new larch looks nice but will presumably actually be grey within a year or two ?

Don't fancy a rooflight then ?

Shame to have steps down onto the patio area - consider raising decking/patio ?

Does the big window have a view and would you want some seating that looks through it ? Seating seems to focus towards the utility door ?

Outside door to the utility ?

[JohnMo]

Basic comments - drawing for planning and warrant will be different, so you will not have combined drawings. So do you have planning permission already - if so drop the planning permission from the drawing title or vice versa.

 

All drawings are light on detail.  Should include details of proposed build-up etc or make reference to additional drawings.

3 hours ago, nwnw said:

Means I have a boxed in steel in the middle of the room but after modelling it doesn't look as bad as I expected.

 If this steel interacts with the outside world it will insulating. Not sure if it also need fire proofing - ask your structural engineer.

3 hours ago, nwnw said:

One kind person pointed out that I had some personal details on the drawings posted so I have redacted and re-attached...

Still has address on one or more drawings

 

Larch Cladding, in 'rain screen' formation with 8mm gaps. - be prepared for a wasp invasion, they will love it.

 

Your ventilation fans really should be upgraded to dMEV, so you have silent ventilation that works. Intermittent fans are awful - the work of the devil.

 

 

[ETC]

Very quick look:

Not keen on the clash of the old and new - would have been nicer (IMO) to keep the existing eaves.

Not keen on the angle in the plan - is there a reason?

CO to living room for stove.

Probably need eaves ventilation at roof junctions.

 

[Roger440]

20 hours ago, Russdl said:

When you get it. You get it. It’s brilliant. 

 

I treid. I tried hard. I didnt get it. So user unfriendly.

[Russdl]

That’s a bit like me with CAD software. 
 

I’m a God with Sketchup

I’m a Dog with CAD. 
 

But I’m determined to get there. 

[nwnw]

On 14/11/2025 at 15:35, Spinny said:

Some random thoughts...

Where will the TV go ? 

Where will kitchen and utility extractors go ?

Outside tap and powerpoint ?

Consider creating a lighting plan now so you can avoid lights clashing with ceiling joists or steel etc

Consider the potential for rain noise from the flat roof - was an unexpected issue for us using single ply PVC membrane - perhaps EPDM is better for noise - acoustic insulation ?

Pity about the beam.

That new larch looks nice but will presumably actually be grey within a year or two ?

Don't fancy a rooflight then ?

Shame to have steps down onto the patio area - consider raising decking/patio ?

Does the big window have a view and would you want some seating that looks through it ? Seating seems to focus towards the utility door ?

Outside door to the utility ?

Thanks @Spinny.

TV like this, or wall adjacent.  Not ideal having the utility door on same wall as it takes away the 'cosyness' of the space.

-Outside tap and sockets - hadn't thought of this but they can go on existing wall near the front door.

-When you say 'lighting plan' and clashing, do you mean physically fitting them in or the way the light falls?  Admittedly I've not thought much about lighting yet.  So far assumed that the recessed spotlights from the existing living area would follow through to new space.

-Rain noise I hadn't considered either.  Can anyone comment on noise potential with this roof buildup?

-I was considering using the larch coating that greys it early and consistently.  I do also like cedar.  Ideally I'd like a trip to Russwood for my wife and I to have a look and decide.

-I had a rooflight in the model then I removed and increased the size of the front windows instead...cost, build complications, light wasn't getting to kitchen anyway due to roof thickness (and that was before I had the lowered beam in the room), maintenance issues (punching a hole in EPDM not ideal).  Windows in image above have open South West and West views and I'm confident that there will be plenty light.

-Patio area...I need a think about how to best use for a seating area.  Models just now simply reflect existing decking.  I suppose there's also an option of stepping down within the entrance area, but then I'd lose internal space.

-Big windows have great views across the countryside.  One sofa and dining table will have good aspect.  Have considered changing the left sofa for a swivel chair.

-Outside door...We considered, but thought it would not get used enough to justify the cost, loss of space and impact on insulation.

 

 

 

Edited 18 hours ago by nwnw

[nwnw]

On 14/11/2025 at 16:59, JohnMo said:

Basic comments - drawing for planning and warrant will be different, so you will not have combined drawings. So do you have planning permission already - if so drop the planning permission from the drawing title or vice versa.

 

All drawings are light on detail.  Should include details of proposed build-up etc or make reference to additional drawings.

 If this steel interacts with the outside world it will insulating. Not sure if it also need fire proofing - ask your structural engineer.

Still has address on one or more drawings

 

Larch Cladding, in 'rain screen' formation with 8mm gaps. - be prepared for a wasp invasion, they will love it.

 

Your ventilation fans really should be upgraded to dMEV, so you have silent ventilation that works. Intermittent fans are awful - the work of the devil.

Thanks @JohnMo.

-Understood.  Don't have planning yet.  Elevations, layout and site/location drawings will cover planning - I'll update descriptions within these.

-More drawings to come.  Was waiting to see what the engineer needed  The 2 detail drawings I included show buildups for walls, floor and roof.  Is this not what you mean by buildup?

-Steel will be internal and part of the heated envelope.  Will ask the engineer about fire-proofing.  I'll maybe add this to my questions for the BCO too.

-Wasp invasion...hmm, you could be right.  My shed with larch cladding already gets chewed to shreds.  Do coating prevent this or is cedar any better?

-Fans - hmm.  I've always seen fans and trickle vents as a means of blowing all the nice warm air out of your property.  Is it worth considering a single room heat recovery unit?

[nwnw]

On 14/11/2025 at 18:17, ETC said:

Very quick look:

Not keen on the clash of the old and new - would have been nicer (IMO) to keep the existing eaves.

Not keen on the angle in the plan - is there a reason?

CO to living room for stove.

Probably need eaves ventilation at roof junctions.

Thanks @ETC

-Not sure what you mean by keeping existing eaves?

-The angled window is the best countryside aspect.  My thinking was that this large, angled picture window would give a nice 'wow factor' and something different in what is otherwise just a box.

-CO?

-Thanks. Yes, I need to have a think about ventilation here.  Currently relies on 'leakiness' of existing roof/wall junction for ventilation I think!

[JohnMo]

59 minutes ago, nwnw said:

2 detail drawings I included show buildups for walls, floor and roof.  Is this not what you mean by buildup?

So the main drawing would need to cross refer to the cross section drawings as different wall may be built in different ways.

 

1 hour ago, nwnw said:

I've always seen fans and trickle vents as a means of blowing all the nice warm air out of your property.  Is it worth considering a single room heat recovery unit?

If your house isn't air tight don't bother with heat recovery. Fans and trickle vents are ventilation, without it everything goes mouldy. A decent smart dMEV fan will run a very low background flow rate, and only boost if needed. Trickle vents can be made to be humidity activated, so only open when needed. Think about the system and plan, it will be silent, it only ventilates at the minimum level all the time. You only have trickle vents in dry room, and dMEV fans in wet rooms. Heat loss is minimised.

[nwnw]

3 hours ago, JohnMo said:

So the main drawing would need to cross refer to the cross section drawings as different wall may be built in different ways.

 

If your house isn't air tight don't bother with heat recovery. Fans and trickle vents are ventilation, without it everything goes mouldy. A decent smart dMEV fan will run a very low background flow rate, and only boost if needed. Trickle vents can be made to be humidity activated, so only open when needed. Think about the system and plan, it will be silent, it only ventilates at the minimum level all the time. You only have trickle vents in dry room, and dMEV fans in wet rooms. Heat loss is minimised.

Yes, that's my intention. A couple of overall layout drawings referring to the x-section details.

 

I think I'm too used to living in old draughty houses (inc this one! ...although something I've been improving on over time).

Has anyone ever worked out the cost/heat impact of a dMEV running constantly?  I'm not worried about the 0.5W to run.  I'm thinking how many kWh of warm air is being blown out in the winter?  I'm curious to see if single room MHRV would be cheaper in the long run?