Passiv house costs.

[garrymartin]

38 minutes ago, -rick- said:

A lot of custom one-off homes will tend to be in the more expensive as the customers will want nice things like big windows, overhangs, lots of corners and detail or simply to squeeze a lot into a difficult site. Meeting the passivhaus standards then will add a lot more cost than a simple box.

Spot on. Passivhaus is only of near-equal cost parity if the building was designed to be Passivhaus from the beginning, including principles of form factor. If someone has designed a home, and then tries to make it Passivhaus, then you are almost in retrofit territory, which of course costs more.

 

18 minutes ago, saveasteading said:

I was thinking of one-offs as most on BH are.

I think you can do one-offs too at significantly less than 30% increase in costs, but as above, you need to design from the outset.

 

The garage door is a great example earlier in this thread. It looks like the architect/designer didn't consider this at the outset, and possibly made the fire *and* airtightness barrier/boundary the same, causing the requirement for an airtight and thermally efficient fire door, which was very costly. Separating those elements (fire/airtight) at the design stage may have resulted in signficantly less cost. It may not have been possible given site or design constraints, but just one example.

[Gone West]

3 hours ago, -rick- said:

An example of cost saving might be that if you meet passivehaus standards, especially in a compact home, your heating demands are tiny so you can skip the expensive heat pump install and just put in a couple of small electric heaters.

Exactly. We designed and built our last place to PH standards. It was around 130m2 and was heated with a towel rail in each of the three bathrooms and an EASHP built into the MVHR came on when the weather was very cold. The whole house was kept at 23C 24/7. Very low energy costs.

Edited Sunday at 12:11 by Gone West

[MPx]

14 hours ago, Oz07 said:

I've been thinking about this. Not an ideal solution but one which should pass? Have a non fd rated passiv level insulated door opening into your hallway, and a fire doorset immediately behind opening into the garage. Depending what is stored in the garage after sign off you may want to remove fd? If the garage size and position of opening allows you may even like to build a small stud lobby within the garages. Insulated door into house, fire line the stud and fire door on the stud going into garage?

Yes, as our walls will be some 400mm thick we could support a double door withing the aperture and we considered the FD on the garage side and the passive door in the hall, but what a pain to use, exacerbated by the self close on the fire door.  

 

12 hours ago, -rick- said:

 

The problem you describe here is one that has come up several times on this forum (for people who are just trying to be energy efficient, not building to passivhaus standards). Integrated garages impose a lot of extra costs that aren't obvious when the architect first draws them. That said, they are often the only option in many plots.

Integral garage a part of our brief.  Drive in and enter the house out of the weather.  

 

So part of the design.  But as it doesn't appear to be possible to make an operational garage airtight or thermally efficient it has to be outside the envelope.

 

Building control also working against us.  Nonsense requirement to have a 150mm step between garage and hall - no doubt mitigating risks that no-one has ever seen materialise.  Working opposite to the requirement to have a level entry to the front door.  By definition there must be a step or slope if the garage is 150mm lower so "level" is not a possible outcome.  We're just trying to make sure we're able to manage life with mobility issues should that come to pass - but hopefully it wont!

Edited Sunday at 21:35 by MPx

[Oz07]

8 hours ago, MPx said:

Yes, as our walls will be some 400mm thick we could support a double door withing the aperture and we considered the FD on the garage side and the passive door in the hall, but what a pain to use, exacerbated by the self close on the fire door.  

 

Integral garage a part of our brief.  Drive in and enter the house out of the weather.  

 

So part of the design.  But as it doesn't appear to be possible to make an operational garage airtight or thermally efficient it has to be outside the envelope.

 

Building control also working against us.  Nonsense requirement to have a 150mm step between garage and hall - no doubt mitigating risks that no-one has ever seen materialise.  Working opposite to the requirement to have a level entry to the front door.  By definition there must be a step or slope if the garage is 150mm lower so "level" is not a possible outcome.  We're just trying to make sure we're able to manage life with mobility issues should that come to pass - but hopefully it wont!

I think I'd go for the double door then consider ripping one out. Does a fire door need a closer on if you have a "fire door keep locked" sign on instead?

[saveasteading]

9 hours ago, MPx said:

Building control also working against us. 

Can you ask them to show you the "regulation" that requires this, or to explain the reasoning?

 

1 hour ago, Oz07 said:

double door then consider ripping one out. Does a fire door need a closer on if you have a "fire door keep locked" sign

This "threat" can make a bco accept a sensible compromise. Nobody likes to look stupid. Maybe they personally agree with you but are misinterpreting the rules. 

Or switch them later.

Door 1 to comply with building regs.

Door 2 for passive.

 

Or invent your own door which foes both jobs.... somehow.

 

Yes it needs a closer.

[garrymartin]

1 hour ago, saveasteading said:

Can you ask them to show you the "regulation" that requires this, or to explain the reasoning?

It's in Part B somewhere, but I think it's 100mm not 150mm. You can also meet the requirement by having the floor slope away from the threshold, so it isn't mandatory. It's something to do with preventing diesel/petrol spills migrating from the garage into the house.

 

EDIT - I decided to find it... Section 5.7

 

[-rick-]

21 minutes ago, garrymartin said:

It's in Part B somewhere, but I think it's 100mm not 150mm. You can also meet the requirement by having the floor slope away from the threshold, so it isn't mandatory. It's something to do with preventing diesel/petrol spills migrating from the garage into the house.

 

EDIT - I decided to find it... Section 5.7

 

Beat me to it!

 

For as long as petrol cars are common it seems like a sensible rule. Fuel leaking into the ground floor is both a huge issue to clean up and in the event of fire likely blocks the exit and causes rapid spread. Having said that, this is one of the reasons my preference would be for a garage that is not part of the house if there is space (can always put a covered/weather protected walkway in between them).

 

Hopefully will get removed once EVs take over.

Edited yesterday at 09:04 by -rick-

[saveasteading]

The whole floor could slope away from the door, perhaps with a small lip at the door. I wonder if it is supposed to allow for a whole tank. I've so ig could bd allowed to drain understand garage door. Or to have no draughts, build a sump into the floor.

[-rick-]

36 minutes ago, saveasteading said:

The whole floor could slope away from the door, perhaps with a small lip at the door. I wonder if it is supposed to allow for a whole tank. I've so ig could bd allowed to drain understand garage door. Or to have no draughts, build a sump into the floor.

 

That's my understanding. Admittedly there are less rusting out cars around these days and modern cars are less likely to dump the tank but the risk is still there and I doubt we'll see any change until petrol is something you have to actively seek out vs popping to the local petrol station.

[saveasteading]

sorry about the spelling collapse. 

 

If so, then it could be allowed to drain under the garage door.

 

The sump would be a neater and more technical answer but I guess carries more risk, although the smell should be apparent.

 

New cars have plastic fuel tanks.  This allows car park fires to result in a series of explosions as beloved of dramatic films.

 

Garage door bottom seals are very approximate so petrol would get through, or you can leave a gap at an edge.

[MPx]

11 hours ago, saveasteading said:

Can you ask them to show you the "regulation" that requires this, or to explain the reasoning?

 

I guess I could but that's not been the approach thus far.  The Architect recommended a full plans approval.  So the dialogue was between our architect and our (private) building control.  All the nonsense was bottomed out in email argument before we started and "approved" so now I just meet our inspector Danny on site and he takes pictures of stuff to show that we've done what's been approved...

 

Annoying that mistakes get made with the rules and even more annoying to me that so much is open to "interpretation".  But I just prefer to think of it that those battles are behind me now.

[scottishjohn]

plastering robot --thats a joke 

no way it would work in real world

 

 

[saveasteading]

2 hours ago, scottishjohn said:

plastering robot --thats a joke 

no way it would work in real world

Let's come back to the subject in 2 or 3 years.

[Dan F]

On 22/08/2026 at 18:41, MPx said:

Well we're finding it hugely expensive so I'm not surprised its not viable commercially.  Our passive house is going to cost way more to build than it will be worth on the market thereafter.  Latest example:  We have an integral garage.  Garage outside the passiv envelope, hallway inside.  Door from garage to hall very nearly impossible to source.  You can buy any number of FD30 rated fire doors for a few hundred quid as required by BC in that location.  You can buy quite a few doors adequately rated for thermal efficiency and airtightness and they cost low thousands.  But try to find a door that covers both angles and that's a tad harder.  After a 6 month search I've found two companies who will make me one.  One for £7k the other £8k.  That's a lot of money for one internal door!

 

They are expensive, but you shouldn't need to pay anywhere neer 7k or 8k.  Other threads have details of much more modeatly priced Moralt ones. Also, remember you don't need the ones marketed "passiv" as long as u-value is good, and it is airtight and FD30 rated.

 

We paid £1685.00 a couple of years ago for full doorset. The "passiv" version was £2206.00 for minor improvement in u-value.

Edited 15 hours ago by Dan F

[JohnMo]

On 22/08/2026 at 18:41, MPx said:

Door from garage to hall very nearly impossible to source.  You can buy any number of FD30 rated fire doors for a few hundred quid as required by BC in that location

But have you gone back to designer and asked what is the minimum spec you need and still comply with what heat loss loss that applies - it's not black and white.  The door by definition is protected and in a different environment to an external door.  Nothing in a Passivhaus has to be Passivhaus certified just perform to a defined standard (which is variable dependant on form factor and many others). If you can only get a £7k door that is a stupid way to build a house (and doubt that is true).

[scottishjohn]

9 hours ago, saveasteading said:

Let's come back to the subject in 2 or 3 years.

you think the wood and plaster board   + joiners will be any better 

[Dan F]

2 hours ago, JohnMo said:

Nothing in a Passivhaus has to be Passivhaus certified just perform to a defined standard (which is variable dependant on form factor and many others). If you can only get a £7k door that is a stupid way to build a house (and doubt that is true).

There is one kind of exception to to this is; MVHR, as if it's not certified you have to deduct 12% efficiency. Correct on other components though, it's the overal peeformance of the house, not compliance of any given component.

 

U-value of our was 1.02 (vs. passive version 0.72), but it all comes out in the wash when you have good insulation and windows elsewhere,  Also door blanks (with no glass) with such low u-value can be a bit too thick and a bit of a pain to handle.  And to @JohnMo point, if you are using PHPP the garage can be configured with it's own temperatue zone, making the impact of u-value on this door even less important.

[saveasteading]

My point on costs is exactly this.

We forgot need mvhr to get bldg regs. So it is an extra cost. £10k? As copmared with the base cost.

Then apply the same principle throughout and there will bd lots of extras.

As for not needing PH certification for every product, is it not the case that the assessor will want a believable performance cert from lots of suppliers? At a minimum, they have researched their product and paid for an assessment.

 

I'd be interested to know what fees are payable overall,  assuming outsourced consultancy. Architect who is prepared or specialises  in this.

Assessor? PH approvals? 

 

If the average or typical one-off house costs 300k then my guess of 30% is an extra 90k.

 

10k mvhr

20k doors and windows

10k stuff I don't even know about. 

Contractors' premium for all the supervision and care. 20?

20k fees beyond the standard, for architect,  assessor  and certification.*

 

80k

 

So approaching 30 %.

That will reduce as a percentage on a more expensive project by size and spec.

It could equally be much lower on mass production with holistic design.

 

I'm genuinely interested and prepared to be proven wrong.

 

* I may have the wrong impression from the consultants I've heard from and read about, as these will be the loud ones with more gimmicks and higher fees.

 

 

 

[-rick-]

30 minutes ago, saveasteading said:

If the average or typical one-off house costs 300k then my guess of 30% is an extra 90k.

 

10k mvhr

 

Most new houses will have MHVR anyway. I think it's still strictly optional in current regs but will be mandatory when the next revision comes out

 

30 minutes ago, saveasteading said:

20k doors and windows

 

If the standard quality windows and doors package for a house is 20k, then getting higher spec windows might add 10k?? If you go for lots of big windows, sliders, etc, you are going to spend a lot more but you are likely buying premium windows anyway and might not need to spend more on top of that premium to meet the passive specs.

 

30 minutes ago, saveasteading said:

10k stuff I don't even know about. 

Contractors' premium for all the supervision and care. 20?

 

The newer building regs requirements for documentation of all joints, etc, is not dissimilar to passivhaus requirements so while this premium used to be there I'm not sure it is hugely significant any more and even if Passivhaus is more demanding, the availability of tools (apps, etc) to aid this process likely lowers the cost compared to historical cases.

 

30 minutes ago, saveasteading said:

20k fees beyond the standard, for architect,  assessor  and certification.*

 

I thought on an average house you'd be looking at less than this. I have in my memory someone saying a passive haus consultant costing about 5k in addition to the architects fees. But not sure the context of that or how current it is.

 

Edit: I think part of my thought process of saying 'PassivHaus costs are not hugely more than standard build for some (more optimal) build profiles' is that the cost of building a 'standard' house has gone up a lot with our Building Regs incorporating a lot of the work that was traditionally only done for PassivHaus designs. (Ventilation, overheating, documentation, higher insulation and air tightness standards, etc).

Edited 4 hours ago by -rick-

[saveasteading]

21 minutes ago, -rick- said:

building regs requirements for documentation of all joints, 

That's just good design isn't it? As opposed to some projects where a planning drawing is just handed over to a builder. Or an Architect's drawing with "detail by SE/ specialist / builder."

 

Some of us have always done this, learning practicalities along the way.

I  can't recall any bco looking on site at anything that wasn't readily visible. I suppose they saw that there were detailed drawings and accepted them.

 

So I guess being asked for PH certification for an already well designed building would be an expensive extra. No client ever asked,  and we researched and decided not to go that direction.

But I can see that,  with funds available,  it is a way of ensuring quality if you are  starting from scratch and don't have a trusted team or procurement process.

[-rick-]

1 minute ago, saveasteading said:

That's just good design isn't it? As opposed to some projects where a planning drawing is just handed over to a builder. Or an Architect's drawing with "detail by SE/ specialist / builder."

 

I was referring to the requirement to show photos as built and have a full library of such photos for inspection. I may be getting something wrong here but I thought that was now part of the newer building regs. People on here have certainly started threads where they were asked for photos and didn't have exactly the right thing for the BCO.

 

Assuming I'm right, if every junction now needs photos of it showing it was built correctly, then inevitably the cost of doing so vs the passivhaus requirement for similar is going to be smaller and the quality of the standard build will inevitably be higher so the added quality supervision aspect is also not as significant as it used to be.

 

I'm sure passivhaus requirements are stricter, but my point is that once this process is in use by normal builders the add on cost of doing 'just a bit more of what you already do' vs 'doing something entirely new and unfamiliar' is much smaller.

[saveasteading]

7 minutes ago, -rick- said:

full library of such photos for inspection.

You are right that the bco hardly visits.

They used to tell me that was largely down to trust, but now it is just minimising cost. 

There were always things where I wondered why they weren't asking anything. I worry about other people's projects.

My photo file is very boring indeed (to most people). "How many pictures of a hole in the ground do you need?"

[JohnMo]

1 hour ago, -rick- said:

Most new houses will have MHVR anyway. I think it's still strictly optional in current regs but will be mandatory when the next revision comes out

Unless you are in Scotland and then a score better than 3m³/m² @ 50Pa has to have MVHR - so applicable to any low energy loss house, so not an extra really for Passivhaus.