Stipulating airtightness in a contract with a builder

johnwstafford

I’m interested to hear what people have done/would suggest/etc on the following topic:

---Including an airtightness stipulation into a contract with a builder for building a house (for argument sake say the specified value to meet was : 1m3/hr to pa 50)---

I’m aware that there are a lot of variables to be taken into account but in general here are some thoughts which have been running through my mind:

- Would a builder typically have an idea on what they need to do to ensure this?
- I’m assuming that this stipulation would be met/failed by the final airtightness test?
- Is this a good way of pinning the responsibility of “airtightness” on the builder?

As I said, I’m just fishing for past experience/suggestions/materials for reading/etc to increase my knowledge

Thanks,
J

Gumbo

You will want to make sure your builder has experience with Air Tight builds and seek references and see samples of previous work down to achieve a particular air tightness.

Dardania

I've heard of people insisting on 2 stage testing by builders

first stage is when the building is sealed, but before any internal work commences. THis way, the builder can rectify issues without performing abortive work

second stage at end, as you note.

If I were doing a new build, I would totally insist on this too. And would tie stage payments to it

galwaytt

Dardania wrote: »

I've heard of people insisting on 2 stage testing by builders

first stage is when the building is sealed, but before any internal work commences. THis way, the builder can rectify issues without performing abortive work

second stage at end, as you note.

If I were doing a new build, I would totally insist on this too. And would tie stage payments to it

This ^^^^^

We have one client in-process at the moment who has done this, and it's a great idea. If nothing else, it gives a great deal of comfort and is a stress-buster for the client and builders as well.

We have one client at just about move-in now who didn't, and, although I'm confident he will get a good result, the fact that you may not, and the thought and the amount of uncovering you'd have to do to remedy it should you not like the result, means an early indicative test be beneficial. And, I suspect, cheaper than rummaging a finished building trying to find the proverbial needle in a haystack afterwards, as it were.

On a general note, I would have no issue with anyone stipulating any particular value so long as everyone is agreed and up front about what it may involve in the actual construction process (time, materials etc).

johnwstafford

Thanks for your responses. It's funny what ya have to think about/know these days before ya can start a build. The emphasise on matters such as airtightness/thermal bridging/etc - its defo for the best but I'm now sceptical on trusting a builder to build a house to a certain spec as a result.

As a follow on question, if I was to stipulate in a contract that a house was to meet an airtightness spec of 1m3/hr to pa 50, how would a builder 'actually' know that they 'could' actually do this for my build ?

galwaytt

johnwstafford wrote: »

Thanks for your responses. It's funny what ya have to think about/know these days before ya can start a build. The emphasise on matters such as airtightness/thermal bridging/etc - its defo for the best but I'm now sceptical on trusting a builder to build a house to a certain spec as a result.

As a follow on question, if I was to stipulate in a contract that a house was to meet an airtightness spec of 1m3/hr to pa 50, how would a builder 'actually' know that they 'could' actually do this for my build ?

If he doesn't know then. .... he's the wrong builder. ..

Dardania

galwaytt wrote: »

If he doesn't know then. .... he's the wrong builder. ..

coming from a design background - if the contractor can't build it right, it's not designed right... If you make it easy for a builder to build, and use standard techniques, they should be able to get it right

Check specs on any products you spec, to see how good the details and guidance to the builder is...

cork2

Dardania wrote: »

coming from a design background - if the contractor can't build it right, it's not designed right... If you make it easy for a builder to build, and use standard techniques, they should be able to get it right

Check specs on any products you spec, to see how good the details and guidance to the builder is...

I agreed 110%, if only more people in the industry were of such a mentality we'd be flying. I'm currently on a site where the main contractor is at a standstill due to the fact he agreed to achieve a certain goal. The designer had a whole book of details supplied and products specified, to now discover the products aren't on the market here and even if they were what was specified wouldn't work. Wrong materials in the wrong places. Airtightness is very doable but like everything else it's relatively new in this country therefore everybody on site no matter what their role needs to do a bit of research and educate themselves. From the top of the scale to the bottom ignorance doesn't justify anything. OP when you find a builder go to see airtight houses they have completed and talk to either a professional involved in the design or the homeowner to see what their original goal was and what it is they achieved. Tbh a reasonable level of airtightness isn't hard to achieve!!

johnwstafford

Thanks again for the responses....I'll be including an air leakage rate of <= 2m3/hr @ 50pa in the contract and I'll be reviewing houses that the builders build and use this to make the decision!!!

BryanF

John have looked at the passive standard of construction?

http://www.seai.ie/Renewables/Renewable_Energy_for_the_Homeowner/SEI_Passive_House_A4.pdf

Out nearly tens years now

What is your architect recommending ?

johnwstafford

Floor (<=0.13 - (uValue))
Wall (<=0.13 - (uValue))
Roof (<=0.12 - (uValue))
Windows and doors (<=1.1 - (uValue))
Air Test Results = specified are 0.25 (not sure what this is TBH, need to follow up on this so I know exactly what this means...).
Thermal
Bridging Factor = Part L Req) 0.08

I'm terms of a passive rating (< 1m3/(hr.m2) @ 50Pa), I'm not sure that I want to pump extra money into the build to achieve this when (based on what I have read) <= 3m3/(hr.m2) @ 50Pa can be achieved through the application of best practice. Personally, I want to obtain a builders services who can, through the application of best practice, achieve <=2m3/(hr.m2) @ 50Pa and not have to spend the extra money achieving passive standards. Now, I don't know how much extra money it would cost to achieve a passive standard, shame on me there, but I'm guessing there is a bit in it and personally I'm content at this point in time with <= 2m3/(hr.m2) @ 50Pa.

If anyone wants to make comment on the above, feel free to. I'm pro learning and listening to what other peoples advice/constructive views are…

johnwstafford

PS - thanks for link Brian

BryanF

Great Walls & windows are no good with the heated air pissing out through their junctions.

Good air-tightness is worth the investment