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ICF bungalow.


Sandybay

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Hi,

Currently have a plan to build around a 142sqm bungalow, Am planning To use integraspec ICF blocks.

Does anyone out there live in an ICF house, is it as good as it sounds? 

Do you need to fit a MVHR  system? 

Appreciate any information. 

Thanks. 

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Hi Sandy, 

Currently building a ICF house so can't comment on how it is to live in but TBH I don't know if it will be any different to any other similar spec'd ( u-value, air tightness, sound proofing etc) house. 

No you don't need a mvhr system you can build the house to standard building regs ie draughty and no need for a mvhr system. 

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42 minutes ago, Sandybay said:

Hi,

During an ICF build is it possible to insulate the concrete core inside the blocks from the foundation,  so you would not lose heat into the ground? 

 

It should be OK to build ICF walls on to a passive slab with a ring beam.  That would remove the floor/wall thermal bridge, and should be pretty straightforward to design.

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  • 2 months later...
  • 3 weeks later...
2 minutes ago, Sandybay said:

Hi, Could someone explain, what the value of works, means when applying for a building warrant in Scotland, and who decides on the warrant charge? 

That is the cost of the actual building work.

 

Mine went in at a rather low estimate as I intend (am) doing a lot of work myself and building control did not query it.  So far my build cost has remained under the building warrant value, and if they ever query it I can show them exactly what has been spent on the build to demonstrate it is below the stated value on the building warrant.

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In contrast to @ProDave, we could only use the RICS index to calculate our build cost as the council would not accept any lower estimate (although I expect to come in a lot lower than the indexed build cost). It may be that they have tightened up a bit in the last year or two.

 

I suspect estimated build cost is used a proxy for the effort that building control need to put in, so I was not overly concerned about it coming out higher than I expect to end up with. The fact that I will end up building it cheaper than estimated is probably irrelevant.

 

See here for an example:

https://www.highland.gov.uk/downloads/file/13353/building_warrant_fee_guidance

 

 

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On 29/03/2019 at 17:59, Sandybay said:

 

Do you need to fit a MVHR  system? 

 

 

The house will need some kind of ventilation to meet BR - https://www.planningportal.co.uk/info/200135/approved_documents/68/part_f_-_ventilation

 

Fundamentally, your house needs a minimum supply fresh air (per m2 floor area) and a means to extract damp air from bathrooms & kitchens (min flow rate per type of room). This reduces condensation (and the impact that has on the longevity of the fabric) plus is safe and pleasant for those living there. The min acceptable figures are specified in the BR spec above.

 

So, if you have a leaky house (by virtue of construction method and trickle vents in windows) plus extractors in kitchen and bathroom then you'll probably meet the standard. However your ventilation will not be energy efficient as in winter that ventilation will also take heat that you've paid for out the window /fan with it and bring in cold air that you need to heat from scratch (and the reverse in summer).

 

If the house is inherently airtight (which is much more likely if using ICF vs classic block & brick etc) then you may need to ventilate mechanically to get the necessary airflow, however the heat will still go out with the stale air and cold come in with the fresh (vice versa in summer).

 

The last two letters in MVHR stand for Heat Recovery which means there is a heat exchanger in the fan unit that keeps the internal air at the same temperature by recovering heat on the way out from stale air and using it to warm the fresh air on the way in.

 

Basic systems are not super expensive and can be DIY installed as part of first fix. There are more expensive options that can add supplemental heat / cool to the air but given relatively the low airflow of a ventilation system, they won't make a meaningful difference but can be used for trim.

 

MVHR is only really efficient at heat recovery when the ACH is below 2 but contrary to some perceptions, you can leave doors and windows open in summer to your heart's content (as we do) and keep your MVHR running to keep bathrooms etc ventilated.

 

Other benefits include filtering of incoming air to remove pollen etc.. again only effective while windows are closed.

 

 

Edited by Bitpipe
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Thanks for the information about The MHVR system. 

With regards to the building warrant, seems the council have a set rate per sqm for building and it's a high one!

And that's what they Base the building warrant fee on, hope they spend money wisely, but I doubt it. 

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MVHR is primarily an air quality device... Reducing humidity, removing pollutants etc. Heat recovery is a bonus feature. Don't read too much in to the efficiency numbers bandied about... They are done in ideal lab conditions and real world are a lot less.

 

MVHR system is totally doable DIY. Basic concepts and then laying ducting through the house. You can easily save £2-£4k.

Edited by Conor
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Welcome.

6 hours ago, jamieled said:

In contrast to @ProDave, we could only use the RICS index to calculate our build cost as the council would not accept any lower estimate (although I expect to come in a lot lower than the indexed build cost). It may be that they have tightened up a bit in the last year or two.

 

Can you actually reclaim that?

 

Perhaps in law the overcharge is for "work" which the Council actually has not dome?

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I doubt it, but worth a shot. The way I see it, estimated build cost is a poor way of identifying the work required by building control unless (as they seem to be doing,  it is all indexed the same way).

 

Take my 3 bedroom house. I could go to a main contractor for a turnkey build and spend £2000/m2, or DIY at slightly over half that (maybe, we'll see where we end up!). The work required by building control is the same in both cases which is why a pick your own build cost approach doesn't work.

 

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19 minutes ago, jamieled said:

I doubt it, but worth a shot. The way I see it, estimated build cost is a poor way of identifying the work required by building control unless (as they seem to be doing,  it is all indexed the same way).

 

Take my 3 bedroom house. I could go to a main contractor for a turnkey build and spend £2000/m2, or DIY at slightly over half that (maybe, we'll see where we end up!). The work required by building control is the same in both cases which is why a pick your own build cost approach doesn't work.

 

 

As far as I know, the build cost for the warrant application is supposed to include a proper value for labour even if you're going to DIY/call in favours/whatever. Although it doesn't have to include the value of work not strictly relevant to the warrant (internal finishes etc) but there's very limited guidance on what exactly should/shouldn't be included. So I suspect a lot of people's figures are pretty notional.

 

It does seem a fairly unreliable way of valuing/costing the work involved - if you specify £10k of high performance windows rather than £2k of cheap PVC that doesn't really make any difference to the council checking they meet the appropriate BS/u-values/whatever...

 

 

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  • 1 month later...

Hi,

We have planning to build an ICF bungalow, but having trouble getting an experienced ICF builder to do the whole build.

If I just got the walls up, would it be reasonably easy for a normal joiner to be able to finish the house? roof on Windows in ect. Or would it not be recommended unless they had previous experience working with ICF,as I appreciate the finish is key to the benefits of this type of build.

Thanks. 

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