Construction and SAPS

[80BSY]

Hi, am new to the forum, and need some advice. I'm doing an extension that forms three, one bed flats, with attic bedroom. Plans are passed, and I'm starting the footings mid March. My problem comes in the construction the architect has chosen, and his justifications. Although flats are an extension, new build regulations apply. He has done it in timber frame, as he says this is the only way of achieving SAP figures, especially as I don't want to run gas supplies. My issue is, most frame companies don't do extensions, and those that do are very expensive in my area. He's also used 100mmx50mm timbers that no one seems happy to use. Question is, how much, if any, problem will I have reverting to brick and block? 

[ProDave]

I am surprised he thinks he can get enough insulation in a 100mm timber frame.  150mm has been the standard for a long time, and my own house is built with a 195mm frame just to get the insulation levels I wanted.

 

If you are not installing gas, how are you planning to heat them?

[newhome]

I don't think the OP knows about the insulation - his architect appears to have done the spec. The architect maybe told the OP they wouldn't need heating either. 

[80BSY]

They are going to be all electric, most likely a solar panel will be necessary. 

[newhome]

4 minutes ago, 80BSY said:

They are going to be all electric, most likely a solar panel will be necessary. 

 

What's the architect calculated as the U Value of the walls? Is it going to meet minimum building standards? As @ProDave says 100mm looks a bit low these days. 

[ProDave]

All electric as in panel heaters? storage heaters? Air source heat pump?

 

It sounds like your architect has not given you much information.

 

A new build (and this is a new build even if it joins to an existing property) has to meet certain energy performance requirements.  Someone has to detail this with a SAP assesment which will demonstrate compliance with building regulations.  Many of us on here strive to exceed building nregs requirements by a long way.

 

So you should have full details of what insulation he is proposing, what heating system is being proposed etc.

 

 

[PeterW]

@80BSY where are you in the UK as this may make a difference to the answers. 

[80BSY]

I'm in Essex. Heaters would be panel, hot water would be point of source, with electric shower. Insulation figures had been achieved, but needed addition of. 75kw solar panels. Architect has done and got drawing through, his guy that does the regs is basically hopeless, hense why I'm here. Question I have is purely can I get sufficient numbers with brick and block. I'm just doing a bit of background before phoning a new company tomorrow. 

10 minutes ago, ProDave said:

All electric as in panel heaters? storage heaters? Air source heat pump?

 

It sounds like your architect has not given you much information.

 

A new build (and this is a new build even if it joins to an existing property) has to meet certain energy performance requirements.  Someone has to detail this with a SAP assesment which will demonstrate compliance with building regulations.  Many of us on here strive to exceed building nregs requirements by a long way.

 

So you should have full details of what insulation he is proposing, what heating system is being proposed etc.

 

 

 

[Ed Davies]

100x50 timbers doesn't limit the insulation to 100mm. Could be another 100mm of EPS stuck on the outside, for example. Worth understanding, though.

[80BSY]

That's exactly how it was done. 

2 minutes ago, Ed Davies said:

100x50 timbers doesn't limit the insulation to 100mm. Could be another 100mm of EPS stuck on the outside, for example. Worth understanding, though.

 

[newhome]

6 minutes ago, 80BSY said:

That's exactly how it was done

 

What were you having on the outside? Blocks and render? 

[ProDave]

37 minutes ago, 80BSY said:

I'm in Essex. Heaters would be panel, hot water would be point of source, with electric shower. Insulation figures had been achieved, but needed addition of. 75kw solar panels. Architect has done and got drawing through, his guy that does the regs is basically hopeless, hense why I'm here. Question I have is purely can I get sufficient numbers with brick and block. I'm just doing a bit of background before phoning a new company tomorrow. 

 

So it has barely scraped through needing something like 3 solar panels to comply.

 

The question you have to answer before moving forwards, is are you happy with something that only barely meets building regs, or would you like to put a bit more thought into it and build something that exceeds building regs with or without solar panels?

 

The simple answer is done correctly, masonry construction will be okay. Choose the construction method to  suit you and the building, not because only one will comply.

[80BSY]

Yes, but I want to lose the timber frame and just go for brick and block. Bricks just form a plinth to match existing house. Timber frame is causing way too much hassle to get built, I can achieve it much easier in brick and block. 

[80BSY]

That's about tge

2 minutes ago, ProDave said:

So it has barely scraped through needing something like 3 solar panels to comply.

 

The question you have to answer before moving forwards, is are you happy with something that only barely meets building regs, or would you like to put a bit more thought into it and build something that exceeds building regs with or without solar panels?

 

The simple answer is done correctly, masonry construction will be okay. Choose the construction method to  suit you and the building, not because only one will comply.

That's about the size of it, brick and block, panel heaters, and no solar panels would be the perfect outcome. Do you assume that's possible? 

[ProDave]

1 minute ago, 80BSY said:

That's about tge

That's about the size of it, brick and block, panel heaters, and no solar panels would be the perfect outcome. Do you assume that's possible? 

Probably, but that is what the SAP assesment is all about, These days brick and block will require a wider cavity than the old days of 50mm, and filled with insulation.

 

Panel heaters are dreadful in SAP. Why not consider an air source heat pump?  they deliver roughly 3KW or more of heat for every 1KW of electricity used.

 

Are these to keep? to live in? to rent? or to sell?  It largely depends if you want low running costs, or sod that, just build them as cheap as possible then sell them?

[80BSY]

They are to rent, thus wanting to make them as uncomplicated as possibly. Its not purely costs, basic works best on rental. I'm happy to use 100mm of celotex in the cavity if it gives me the numbers. 

10 minutes ago, ProDave said:

So it has barely scraped through needing something like 3 solar panels to comply.

 

The question you have to answer before moving forwards, is are you happy with something that only barely meets building regs, or would you like to put a bit more thought into it and build something that exceeds building regs with or without solar panels?

 

The simple answer is done correctly, masonry construction will be okay. Choose the construction method to  suit you and the building, not because only one will comply.

That's about the size of it, brick and block, panel heaters, and no solar panels would be the perfect outcome. Do you assume that's possible? 

[80BSY]

They are to rent, thus wanting to make them as uncomplicated as possibly. Its not purely costs, basic works best on rental. I'm happy to use 100mm of celotex in the cavity if it gives me the numbers. 

[PeterW]

Right ... 100/150/100 with blown graphite EPS, 400mm loft insulation and decent (ie 1.1 or less) windows and you will be getting toward something workable without the solar. 

 

Your big issues will be power - diversity on 3 x 10kw electric showers plus panel heaters etc means you’re going to need to run 3 mains connections. What is the water pressure like ..? Again, 24lpm is your minimum flow so you’re heading toward 32mm main territory. 

 

Are these one  bed flats ...??

[ProDave]

1 minute ago, PeterW said:

Right ... 100/150/100 with blown graphite EPS, 400mm loft insulation and decent (ie 1.1 or less) windows and you will be getting toward something workable without the solar. 

 

Your big issues will be power - diversity on 3 x 10kw electric showers plus panel heaters etc means you’re going to need to run 3 mains connections. What is the water pressure like ..? Again, 24lpm is your minimum flow so you’re heading toward 32mm main territory. 

 

Are these one  bed flats ...??

Each flat will needs it's own independant supply anyway now.  So one shower and some heaters is quite possible.

 

Agreed for rental simple is best, so put your efforts into a well insulated building with decent Windows and see how you get on.

 

Air tightness (which means attention to detail on the build) will be an important part of that. Give consideration to installing mvhr which will help hugely, and is only a 6 month filter cleaning excercise so not onerous for rental.

 

Probably modern storage heaters which these days have electronic controls would be the best option?

[Declan52]

1 hour ago, 80BSY said:

They are to rent, thus wanting to make them as uncomplicated as possibly. Its not purely costs, basic works best on rental. I'm happy to use 100mm of celotex in the cavity if it gives me the numbers. 

Don't use the pir type in the cavity.  Do as Peter has said above and get eps beads blown in to a 150mm cavity.  This will result in a far better job than using celotex type boards. 

[80BSY]

8 minutes ago, ProDave said:

Each flat will needs it's own independant supply anyway now.  So one shower and some heaters is quite possible.

 

Agreed for rental simple is best, so put your efforts into a well insulated building with decent Windows and see how you get on.

 

Air tightness (which means attention to detail on the build) will be an important part of that. Give consideration to installing mvhr which will help hugely, and is only a 6 month filter cleaning excercise so not onerous for rental.

 

Probably modern storage heaters which these days have electronic controls would be the best option?

Yes, they're all having they're own water and electricity supply, even the additional flats in the existing building will. I want them all as stand alone flats, own front doors, parking, and no communal areas. 

[Ferdinand]

10 hours ago, 80BSY said:

They are to rent, thus wanting to make them as uncomplicated as possibly. Its not purely costs, basic works best on rental. I'm happy to use 100mm of celotex in the cavity if it gives me the numbers. 

 

What is the actual SAP number you need to achieve (it sounds as if your architect is trying to scrape a minimum)?

 

If the SAP chap is useless, then I would check it - as you are wisely doing. Does your extension count as a newbuild or an extension, since each flat is a separate dwelling? The required standards are different. Which set of values applies, and have they done it correctly? And you will have to decide whether your solar will be MCS-accredited or not. Cost difference of 1-2k, there.

 

Which way do the solar panels face? Are they actually useful? This is a bit a red flag, as use of solar PV has long been a way to boost your EPC number when the basic house is not good enough. 

 

Agree that the best way is not to have it, esp. if there is no real benefit.

 

As a LL myself, I would be concerned with panel heaters in a rental which is not built to high standards. Providing inexpensive running costs is imo the best way to keep tenants for years and years and years, especially as Change of Tenant costs continue to become more onerous over time.

 

Ferdinand 

 

Edited February 11, 2019 by Ferdinand

[80BSY]

5 hours ago, Ferdinand said:

 

What is the actual SAP number you need to achieve (it sounds as if your architect is trying to scrape a minimum)?

 

If the SAP chap is useless, then I would check it - as you are wisely doing. Does your extension count as a newbuild or an extension, since each flat is a separate dwelling? The required standards are different. Which set of values applies, and have they done it correctly? And you will have to decide whether your solar will be MCS-accredited or not. Cost difference of 1-2k, there.

 

Which way do the solar panels face? Are they actually useful? This is a bit a red flag, as use of solar PV has long been a way to boost your EPC number when the basic house is not good enough. 

 

Agree that the best way is not to have it, esp. if there is no real benefit.

 

As a LL myself, I would be concerned with panel heaters in a rental which is not built to high standards. Providing inexpensive running costs is imo the best way to keep tenants for years and years and years, especially as Change of Tenant costs continue to become more onerous over time.

 

Ferdinand 

 

The extension 3 count as new build, the other 3 are conversion, as they're part of the original house. I'm uncertain of the numbers I need to achieve for either, but I'm also not confident in the architect. The flats are small, heating costs won't be an issue. Solar panels would be south facing, sun hits it from about 10am, and has no obstructions after that.

15 hours ago, ProDave said:

Each flat will needs it's own independant supply anyway now.  So one shower and some heaters is quite possible.

 

Agreed for rental simple is best, so put your efforts into a well insulated building with decent Windows and see how you get on.

 

Air tightness (which means attention to detail on the build) will be an important part of that. Give consideration to installing mvhr which will help hugely, and is only a 6 month filter cleaning excercise so not onerous for rental.

 

Probably modern storage heaters which these days have electronic controls would be the best option?

Yes, they're all having they're own water and electricity supply, even the additional flats in the existing building will. I want them all as stand alone flats, own front doors, parking, and no communal areas. 

[Ferdinand]

49 minutes ago, 80BSY said:

6 hours ago, Ferdinand said:

 

The extension 3 count as new build, the other 3 are conversion, as they're part of the original house. I'm uncertain of the numbers I need to achieve for either, but I'm also not confident in the architect.

 

I'd say you need to know that, otherwise they may fall foul of the Regulations for rentals.

 

I work to a C for new refurbs, ideally a B.

Ferdinand

 

[Ian]

@80BSY

With the new build ones I imagine that your issue with SAP and all electric panel heaters is that it can be very difficult (impossible?) to get a pass score unless you also have some solar panels or other renewables.