Critique my final(ish) design

[puntloos]

Hey all, I've been with Buildhub for a little over 2 years now - time flies - and it's been quite a ride so far... and I'm finally very close to the final design. Would love some discussion on if we've missed anything ;) Here are the mostly professional designs (amateur renders at the bottom)

 

A few basic design principles:

- Pretty much Passivhaus, intending to run full PHPP, but don't care about certification.

- Full awnings on sun-facing side (SE facing garden), triple glazed with built-in shutters everywhere

- NE loft section will be a plant room - that's where the 600x450 service shaft ends up.

- Split ASHP in the garden. 

 

More details, including SE drawings here

 

Ground Floor (2700mm ceiling)

- the stair nook with the cylinder will likely (...) be used for UFH manifolds, moving the cylinder and ASHP endpoint to the loft. 

- Utility+Bike could be turned into a garage.

- Office with full house service shaft, elevator provisions and a fully ventilated networking cupboard (in current floorplan it is too small, real size 605x700x2700)

 

 

First Floor (2410 ceiling)

- Bed 2 and 2-play can be split into 2 rooms

- Master bed design fairly specific to us, different schedules so while a large space is nicer, telescopic pocket doors approximate the size feeling (see pic below), while allowing us to close them and quietly get changed while not disturbing the partner.  

 

Loft (2300 ceiling)

- Intended to not be built up (cost saving) but fully ready to be occupied, so rooflights present, will adhere to fire regs etc. 

- Bottom right (W17) section sits next to the service shaft, intended as plant room

 

 

 

- Gable actually contains a small seating area - call it a flourish. "Loft stairs" from Bed 4. Good idea? Bad? (we wanted light from the front gable window to come through the area anyway, why not put a beanbag or 2 there.. 

 

Amateur renders (based on my amateur implementation of pro design.. be gentle..)

 

 

 

 

 

 

 

[Iceverge]

Very comprehensive. 

 

Not too many holes to pick really for me. 

 

Budget I'm spitballing will be about £500000 by the time you move in. 

 

I always like a shower + bedroom on the ground floor but I guess you've provisioned for a lift. 

 

Have you thought of solar PV? 

 

My mate put in 2 seperate dressing rooms from the master bed. I wish I'd thought of that. Especially with different waking times. 

 

Some of the details might be tricky to achieve passive levels of thermal bridging + airtightness as drawn. 

 

Run PHPP soon if you can. Your southern glazing looks like it might cause overheating despite the awning. 

 

 

I'm impressed with your "amateur" drawings. What did you use? 

[tonyshouse]

I would commission a building physics model to inform shading and danger of overheating, better fo find out first than after it is built.

 

awnings only work when it is not windy

 

how will you mitigate the thermal bridging introduced by the steelwork? Is the insulation barrier outside or inside the structure? 
 

beam and block floor can introduce draughts. 
 

looks like nice design, 

[Bitpipe]

Looks great, I see the basement did not make the final cut

 

Only observation is that your wet services on ground and first floors looks to be on opposite sides of the house - i.e. your master ensuite is above the office, the fam bathroom and guest ensuite are above the living area and your kitchen utility have no wet services above them.

 

While this is not an issue for supply it may make for some complicated foul runs and these have the biggest impact due to diameter, falls etc.

 

We ended up with quite a bit of structural steel in our build and had some tricky problems as we did not plan for penetrations for MVHR or fouls - worked it out in the end but required some creative boxing out to get the fouls where they needed to be.

 

Have you done a draft M&E design to plan where MVHR (large bore to outside and 75mm bore to inside, double runs for wet rooms) and fouls will run? Manifold for hot & cold supply, hot return path etc. to minimise runs & heat loss? 

 

Make sure you have that before you move to structural design as you may have to spec steel penetrations to get wider bore services through.

[puntloos]

49 minutes ago, Iceverge said:

Budget I'm spitballing will be about £500000 by the time you move in. 

 

Ha - well in Jan 2021 my QS figured more like 720K - at this point I'm expecting 800. This is in a Hertfordshire commuter town with a very good train link, so everybody asks a premium. I do plan to look for some builders more up north to tender. 

 

Quote

I always like a shower + bedroom on the ground floor but I guess you've provisioned for a lift. 

 

We are provisioning a shower in the bike/utility room actually, but that's more to hose down the kid or scrub the gimp - you know. But at some point it could be converted in either a garage or an extra room.

 

Quote

Have you thought of solar PV? 

Absolutely, solar PV covering the sunfacing. 

 

Quote

My mate put in 2 seperate dressing rooms from the master bed. I wish I'd thought of that. Especially with different waking times. 

 

Ha, people less romantic than me say that older couples would just want 2 bedrooms and one.. 'shared' one.  - not sure how 2 dressing rooms help with the waking times though, core point is that you need privacy, light, and some noise isolation while you undress. 

 

Quote

Some of the details might be tricky to achieve passive levels of thermal bridging + airtightness as drawn. 

 

Someone else here pointed out some bridging problems - but would love to hear details on your concerns if you have the time...  did you look at the SE drawings? (mind you, I don't think the SE was actively thinking about thermal.)

 

Quote

Run PHPP soon if you can. Your southern glazing looks like it might cause overheating despite the awning. 

 

Yes, it is the concern. As perhaps noted elsewhere I am "somewhat less" concerned about hitting true passivhaus, so I wouldn't mind overdimensioning my ASHP somewhat and I was planning to insert chiller coils such as this one Carrier Idrofan 42EP in the living room void. Runing off PV during those hot days might strike a suitable balance without running up bills...

Quote

I'm impressed with your "amateur" drawings. What did you use? 

 

This is Chief Architect software - and the pictures are raytraced (it supports GPU raytracing so it only takes 20-30 secs per picture). VR mode is also quite interesting

I'm... somewhat..  proficient at this point with the program but many of the details don't reflect reality, for example I convinced it to build the crown roof by inserting a fake floor.. sounds good in theory but in practice many roof planes are now really weird and had to be manually pushed back etc - so for a quick impression it's great, just any smallish details (e.g. look at the glass balustrades) are bound to be messy and not to be depended on.

Edited November 19, 2021 by puntloos

[puntloos]

40 minutes ago, tonyshouse said:

I would commission a building physics model to inform shading and danger of overheating, better fo find out first than after it is built.

 

Chief Architect can certainly show the solar angles if that's what you mean - but it doesn't have any cleverness around overheating. All I know is that the floor of my livingroom and garden room will never see direct sunlight as long as the awnings are out. As for the skylight, all I can do is have it be electrically tinted, smartglass with also a solar coating.. (I forgot the actual terms, but you probably know what I mean).

 

Who would do such physics models?

 

40 minutes ago, tonyshouse said:

awnings only work when it is not windy

 

True, but windy+hot is pretty rare around these parts. I certainly intend to ensure the wall that holds the awnings is prepared for major wind force. (plus as mentioned I was planning to use the ASHP for cooling as well, maybe UFH, but to avoid condensation, more likely chiller coils

40 minutes ago, tonyshouse said:

how will you mitigate the thermal bridging introduced by the steelwork? Is the insulation barrier outside or inside the structure? 
 

I have no idea whatsoever! - how can I tell?  (did you check the SE designs?)

This is one of my major struggles, I've tried to hunt for cold bridges myself, but I'm an amateur and don't really know what to look for when things get too detailed. My architect is good at his job creating a "pretty" house, but I'm not super confident they are great at all the thermal details.

 

40 minutes ago, tonyshouse said:

beam and block floor can introduce draughts. 
 

How does one mitigate that?

 

40 minutes ago, tonyshouse said:

looks like nice design, 

Tx for taking a look!

[SteamyTea]

7 minutes ago, puntloos said:

True, but windy+hot is pretty rare around these parts

The UK has a SW prevailing wind, this is a warm wind.

I look forward to a proper winter storm, it heats the house up.

It is those NE upcountry winds that cause us trouble down here.

[puntloos]

44 minutes ago, Bitpipe said:

Looks great, I see the basement did not make the final cut

 

Nope, at 65K for 250sqft, with a huge unused loft it didn't make enough sense. It's elegant to stuff all plant in there, but eh.. can't have it all

 

44 minutes ago, Bitpipe said:

Only observation is that your wet services on ground and first floors looks to be on opposite sides of the house - i.e. your master ensuite is above the office, the fam bathroom and guest ensuite are above the living area and your kitchen utility have no wet services above them.

 

While this is not an issue for supply it may make for some complicated foul runs and these have the biggest impact due to diameter, falls etc.

 

To make sure, let me indicate where the 'wet rooms' above ground are:

 

 

The master has a downpipe near, the family+ensuite too. 

I do plan to have fittings for upstairs washingmachine (if one ever wants to convert utility to proper garage). The most concerning foul run to my layman's eyes is from the washing machine above office to either the service shaft (top left of office) or master ensuite foul run (top right of office). If anything, maybe move washing machine near the service shaft.

 

 

44 minutes ago, Bitpipe said:

We ended up with quite a bit of structural steel in our build and had some tricky problems as we did not plan for penetrations for MVHR or fouls - worked it out in the end but required some creative boxing out

 

What's boxing out?

44 minutes ago, Bitpipe said:

to get the fouls where they needed to be.

 

Have you done a draft M&E design to plan where MVHR (large bore to outside and 75mm bore to inside, double runs for wet rooms) and fouls will run? Manifold for hot & cold supply, hot return path etc. to minimise runs & heat loss? 

No, I've been going back and forth on that one. On the one hand my wife wants to first decide if we go ahead and build at all (if tendering doesn't give us a terrible surprise) but on the other hand indeed having to redo the SE is also not great...

 

44 minutes ago, Bitpipe said:

 

Make sure you have that before you move to structural design as you may have to spec steel penetrations to get wider bore services through.

 

I might ask an M&E guy for a very rough draft... but I'm sure it'll still cost..

[puntloos]

12 minutes ago, SteamyTea said:

The UK has a SW prevailing wind, this is a warm wind.

I look forward to a proper winter storm, it heats the house up.

It is those NE upcountry winds that cause us trouble down here.

 

Ha, down where? Should I be worried?

 

At the end of the day, I'm sure I'll have a few days where it's both sweltering and windy, but I have designed my center hallway as a "heat chimney" and am certainly planning somewhat overdimensioned cooling. Or do you think this will get me into consistent trouble?

[SteamyTea]

3 minutes ago, puntloos said:

 

Ha, down where? Should I be worried?

 

At the end of the day, I'm sure I'll have a few days where it's both sweltering and windy, but I have designed my center hallway as a "heat chimney" and am certainly planning somewhat overdimensioned cooling. Or do you think this will get me into consistent trouble?

I am in Cornwall, we don't have extreme heat, or cold. Just wind and rain.

 

Get a proper thermal model done.

[puntloos]

3 minutes ago, SteamyTea said:

I am in Cornwall, we don't have extreme heat, or cold. Just wind and rain.

 

Get a proper thermal model done.

Absolutely, I have a SAP model done already, and PHPP whenever the guy has time (he's booked until Dec  )

Or do you mean something else than PHPP?

 

[SteamyTea]

7 hours ago, puntloos said:

Or do you mean something else than PHPP

I think PHPP incorporates solar gain, and is pretty accurate, so should be fine.

[tonyshouse]

Instead of beam and block use either in situ or concrete planks 

[Mr Punter]

Have you seen and operated the proposed pocket doors?  They could prove a pain.

 

The floor spans are quite long for the beam and block.  Make sure you specify max deflection of 8mm.  They may spec bigger beams or more of them.

 

A fair amount of concrete for the foundations but still should be cheaper than piling and ground beams.

 

Nice house!

[puntloos]

14 minutes ago, Mr Punter said:

Have you seen and operated the proposed pocket doors?  They could prove a pain.

 

Yes, absolutely a worry in the bedroom, never seen or 'felt' telescopic ones - done the standard 2-piece-connected ones and they are fine but not 'amazing'. 

It's just that in principle having a large-ish master is important *and* the shielded walk-in is important (but both were fairly hard to achieve without even more painful sacrifices such as giving up on bed 3.

 

All the other pocket doors (downstairs) I'm not worried about because they are very much intended to stay open most times, so no need to be annoyed while pushing them around

 

14 minutes ago, Mr Punter said:

The floor spans are quite long for the beam and block.  Make sure you specify max deflection of 8mm. 

What happens if we hit 9? Why 8?

14 minutes ago, Mr Punter said:

They may spec bigger beams or more of them.

Yes, well, you might have seen the SE drawings - https://focusky.com/uqqn/obaq - do you think they would not do?

 

14 minutes ago, Mr Punter said:

A fair amount of concrete for the foundations but still should be cheaper than piling and ground beams.

 

Nice house!

 

1 hour ago, tonyshouse said:

Instead of beam and block use either in situ or concrete planks 

 

I've heard this said before but I think the architect was dismissive of this idea, beam block being faster and cheaper than multideck? Why do you recon it's better?

[ETC]

A bit of a sketch.

[ETC]

And another.

[tonyshouse]

Planks are better in my opinion so long as ends are sealed 

 

ground bearing slab best but not always possible, less heat loss and impossible for draughts in the middle of the house

[puntloos]

Thank you @ETC, for taking the time to think about this stuff, much appreciated. A few interesting ideas. In general sometimes I see why you did it, sometimes I don't.. added comments into the pics!

 

[Mr Punter]

20 hours ago, puntloos said:

Yes, well, you might have seen the SE drawings - https://focusky.com/uqqn/obaq - do you think they would not do?

 

The floor designer normally does the beam layout so you need to give the 8mm spec to the people doing the floor beams.

[Mike]

I'd suggest:

• moving the future lift so that it's adjacent to the existing stairwell; based on the current positioning the Office & Bed 3 would effectively become a second hall (one is enough).
• if you're thinking ahead to a possible lift, it might be worth enlarging the doors so you could at least get out of Bed 3 and into the bathroom in a wheelchair
• rationalise the various recesses against the back wall of the office
• adopting one of ECT's suggestions, or similar, for Bed1 - you don't want to walk into the bedroom via a cupboard
• ditto removing the recessed doorway into Bed 2
• consider a roof terrace above the dining room - in which case you might want to move Bed 1 into this corner & associated changes. Would have to consider the height of roof insulation to that flat roof.
• planning a wardrobe for the recess that backs onto the family bathroom shower, to provide sound insulation, if you're not already doing so
• moving the HWC - you're unlikely to get a well insulated one of adequate volume into the space planned - into the utility room, which I presume will hold other other plant
• make sure you're fully aware of the problems of pocket doors (cleaning, ratting over the tracks, poor sound insulation, maintenance issues...), not just their benefits.

BTW, I assume that the planner don't require you to have a garage?

 

 

 

Edited November 21, 2021 by Mike

[ETC]

[ETC]

[ETC]

[Bitpipe]

On 19/11/2021 at 22:30, puntloos said:

What's boxing out?

 

It's when you have a foul or other large service run flush to a wall (usually external) and then build frame work over them for plasterboard. Worst case you end up with an odd corner to a room or ceiling, we managed to be creative with a few.

 

One pipe entered the living room from ensuite above, we dog legged it to the foul exit and then had the joiner build a faux fireplace nook around it - looks quite smart.