I need to order some footing blocks, what types?

[epsilonGreedy]

1 hour ago, PeterW said:

Does your local builder add 55mm of additional internal PIR wall insulation to his “top end” builds too to make sure his 100mm floor insulation is sufficient to meet the overall DER/TER..?

 

 

I think he is expecting a boost from an air source heat pump. Anyhow I am not planning to buy his house.

 

1 hour ago, PeterW said:

Happy to have the debate. I’d suggest a light read of SAP 2012 (Appendix R may be useful) and then run your build through with 0.30 as the floor numbers and see where the DER comes out. 

 

 

Hang on one hour ago you told me to read the part L building standards, I did and found no reference to your claimed 0.11 floor u-value requirement.

 

1 hour ago, PeterW said:

... and then run your build through with 0.30 as the floor numbers and see where the DER comes out. 

 

 

I have no intention of aiming for 0.30, I was just demonstrating I had actually read the document.

 

I know you are talking general sense on this subject, there is no need to deliver common sense so provocatively. A few days ago you decreed that my block & beam floor was a signature of crap low-end building team.

[epsilonGreedy]

5 minutes ago, PeterW said:

And I stick by what I said - high end UFH and 100mm PIR do not equal quality build. On Saturday I did a pre-plaster inspection for a house that is circa £825k when complete - it has UFH too - and I’ve done a list of about 40 items to be rectified before it’s closed up. I will need to go back and check them before it’s finished however I’ve got a good relationship with the site manager now who understands I’m picking up on detail that their client expects on a major project such as this. 

 

The house has been inspected by a major warranty provider and BRegs supplier and has been passed however none of what I have picked up would be classed as not meeting the Approved Documents. Getting a decent air test result with 2 blocks missing in a wall into an integral garage could be fun though ... devil is in the detail ..! 

 

 

Ok but this does highlight the disparity between your notion of a proper house and industry norms (this is before we descend to blatant shoddy practice).

 

I am trying to follow a build route that is better than industry standards but avoids the high-end £££ deluxe builds of many here.

[PeterW]

I currently have a build that is “standard” construction but has a target top B rating (not putting solar on to get an A) that is traditional build. Total cost to date - including £8k kitchen - is coming in at £775/sqm. It’s not deluxe, it’s standard construction, but it’s about attention to detail.

 

Floor is 150mm PIR, walls are 150mm blown bead with some areas 25mm overboard,  roof is 200mm Earthwool with 25mm or 50mm overboarding. All glazing is triple glaze uPVC. Airtightness is plastic membrane, foil taped joints on all PIR internally. MVHR is a commercial Mitsubishi unit, heating is UFH and ASHP. 

 

My - and the clients - notion of spending close to £1m is to get something that actually meets specification. It’s not to do with practices, it’s to do with getting what you paid for..!

 

The reason I don’t like B&B is that unless it’s for specific ground conditions, it is more expensive and labour intensive than a ground bearing slab. The reason a lot of house builders use it is that they also don’t need to remove as much top surface generally with B&B so their muck away costs are less. On individual builds, a single slab of concrete with the UFH built in is cheaper and more effective as it is also dry enough to finish long before the end of the build unlike screeds that can need force drying. Most mainstream builders see UFH as the plumbers job and they aren’t on site until the shell is up and watertight as all underground services are completed by the groundwork teams. Having a plumber into a site for 1-2 days to fit UFH at ground works level would not be easy or cheap to schedule - hence why B&B at groundwork level followed by insulation pipe and screed at first fix is the norm. 

 

As you're building a single build you don’t need to follow this and tbh you can get a better finish for the same money the big boys play at per plot if you work hard however you need to save on the fabric where possible and work out the best way to maximize spend.

 

Cost vs Time is the only equation a self builder really needs to focus on, quality  should never be compromised. 

[Declan52]

1 hour ago, epsilonGreedy said:

 

Ok but this does highlight the disparity between your notion of a proper house and industry norms (this is before we descend to blatant shoddy practice).

 

I am trying to follow a build route that is better than industry standards but avoids the high-end £££ deluxe builds of many here.

But you don't need to spend a fortune to get a good quality build. It's all in the detail. Mine is most definitely not a high end deluxe build, it's just done right with lots of time and effort put in to get it that way.

To get a house that barely passes building regs and comes in at a c rating won't require vast loads of money and time to get it to a B and even possibly an A with the addition of some pv. What score you get in the air tightness test will be a massive indicator of how your build has went. 

How are you sealing up the inside skin of blockwork??

At all the junctions, floor to wall, wall to ceiling, wall to Windows/doors how do you plan to sort these out??

Will your Windows have trickle vents and will your front door have a letter box??

Are you going to seal up every conduit in the house plus around all sockets and ceiling lights???

 

All that's above is what is the difference between a mass built house and what you hope to end up with.

Not one care is given towards these. Dot and Dab plasterboard is used so you end up with a thermal tent.

If you're lucky you get scrim cloth at the ceiling junction but as your house dries and and moves it cracks and then any heat escapes.

You won't have anything at the window door junctions.

All conduits and service pipes won't be properly sealed up.

Not one of these issues will cost a fortune to remedy but each will have a massive impact on how you're house performs.

[epsilonGreedy]

5 minutes ago, Declan52 said:

How are you sealing up the inside skin of blockwork??

At all the junctions, floor to wall, wall to ceiling, wall to Windows/doors how do you plan to sort these out??

Will your Windows have trickle vents and will your front door have a letter box??

Are you going to seal up every conduit in the house plus around all sockets and ceiling lights???

 

 

If I go for aerated thin-joint block this has inherently good airtightness according to the blurb.

 

First floor joists can be hung from hangers that are cemented into slots routed into the block hence no airleak. Floor to wall, not thought about the ground floor, had assumed the overblock membrane lapped to the inner block dpc was effective. I have not read about ground floor to wall air-tightness being high on the worry list in my previous reading.

 

No trickle vents, MVHR instead. No letterbox, going to fix one of those parcel delivery boxes into a garage wall.

 

Wall to ceiling air tightness is a significant unresolved question and so are ceiling lights upstairs.

 

Door frames and window frames are a design headache for another day.

 

Wall sockets will be within the block airtight envelope.

[PeterW]

3 minutes ago, epsilonGreedy said:

First floor joists can be hung from hangers that are cemented into slots routed into the block hence no airleak.

 

Never seen that - got any details ..??

 

7 minutes ago, epsilonGreedy said:

Door frames and window frames are a design headache for another day.

 

This has the potential to affect your blockwork / build up so I’d try and get it resolved sooner rather than later. 

 

26 minutes ago, Declan52 said:

What score you get in the air tightness test will be a massive indicator of how your build has went. 

 

As @Declan52 says,  bear in mind that commercial builders test 1 in 4/5 so you’re building 1, so your test needs to be the thing you aim for. £250 on tape is a good investment. 

[Declan52]

Look how much extra good detail you have  already done and none of it is costing you mega bucks. 

There are none of the issues above  high on any list. They are just small details that once you add them all up make a big difference. That's the big thing about doing a self build, you spend ages on the small things and read and read and make the right choice hopefully. If it's a mass built house then it's just choosing the kitchen and bathrooms you worry about. 

Never seen holes cut out of blockwork to hold hangers. You can get hangers that are built in, not a good idea, and standard hangers nailed on to a piece of timber but that's a new method. As @PeterW says can you post a link to how these work.

If your window fitters are bang bang 10 hilti nails and half a can of expanding foam later then you need to be on the ball here. 

 

[epsilonGreedy]

4 minutes ago, PeterW said:

Never seen that - got any details ..??

 

 

https://www.youtube.com/watch?v=gbQf_YHd6a8

 

They recommend a Strong-Tie by Simpson.

[PeterW]

9 minutes ago, epsilonGreedy said:

 

https://www.youtube.com/watch?v=gbQf_YHd6a8

 

They recommend a Strong-Tie by Simpson.

 

Never seen that done ..! I’d want to see the confirmation from Simpson that their tie is designed to be installed in such a way and their BBA certificate supports the installation method.