ref building hse:need help to make final decisions

D

designchick

Registered User
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9
  • read all posts so far and I mean all.... and have decided to post one of my own as it's all getting to much for my brain.​
  • heres to story so far​
small house currently on a steep site that I'm going to knock and keep the foot print the same and build an L.A. style house on a stepped back level.

main scenic view facing north with sun setting at the front door which has the road access.want to go passive and looking at ICF systems but still not sure as it is quite a complicated build and thinking it might need a retaining wall.this might cost me 20thousand and I'm having heart burn ...
Could the icf 9" suffice .and I could back fill it( that is would I need to back fill or should I want to keep it clear so I don't have cold bridging )or should i just stick with the block and the local builder knowledge.
Head hurts.
syd if your out there give us your take..
mind the buses​
 
it si extermly hard to get passive with ICF. the lowest u value ive seen only approached 0.2/ you certainly will not get it with a single leaf system, theres thermal bridges all over the place, especially with a stepped design. you are probably talking about 12" of a double leaf system for passive standards....

'passive' is a word that bandied about a lot. the only way of a house being truely passive is for it to be certified by the passive institue. [broken link removed]
their method of testing is very strict.

AFAIK the only 'passive' house in ireland, the mosart one, is still undergoing testing to determine if its actually passive.. im open to be corrected on this. I do know that it needed remedial work to counteract overheating.

The SEI have recently published their own passive house guideline, ( [broken link removed] ) however these are patchy in parts, so the passive institute and the phpp method is still the best way to determine.

For a low energy aim, my best advice is to hire the competent professionals you need, architects, engineers, QS, energy auditors..... look for references for each and every professional, their skills can vary widely.
You need to select a yearly energy figure (usually determined by fuel costs), and work from there back to the build specification.

for example. say you do not want to spend any more than €400 per year of energy for your house. this will equate to 'whatever' BER rating.... in order to meet this rating you need certain u values for elements of construction..... say 0.16 for walls, 0.12 for floor etc..... your architect, or, more importantly, your architectural technician, should be able to describe what construction make-ups will meet these u values..........
again for example a TF house with 'x'mm of insulation, versus cavity wall with 'x'mm of insulation, versus x specification of ICF, versus x sepficication of poroton etc etc etc...
your QS should then be able to price up whichever of these constructions you want, and give a 'per sq m' pricing on each....(remember each method of construction has its own pros and cons....)
you can them specify your build and go to tender based on this information.....
theres a hell of a lot involved so the skills of your professionals is paramount.... also paramount is your ability to make decisions and stick by them!!!

best of luck, remember, one of the most important factors in determining a low energy dwelling is the amount of passive solar gains, so your dwelling should be designed for same.... this will be determined by the skill of the architect....
 
thank you,
I think I under stand what you're saying.Maybe I'm one of those that are banding the word passive about.
I have my arch tech /arch employed and there has been alot of consideration gone into the final design.Because we live in a little house on the site at mo it makes it earlier to design cos we know where the light is at different times of the day.This I have to say has been reallly helpful in the over design.
I think your right I will just have to get both systems priced block/ICF and see what comes out.I'm still thinking that the ICF would be easier at it only involves pouring and no real man labour,lifting down onto the site etc.
 

one of the most important factor in a good icf house is the competence of the constructor.....
some icf crowds will give you a dvd and off you go.... not very professional.
you would be well advised to hire dedicated erection crews to construct the icf, for example the walls need to be , i think, 1.5 deg off square before pouring because pouring pushes them off square etc....

andother factor in choosing icf is whether they are IAB certed or not.... afaik theres only 2 systems in ireland iab certed... there are others BBa certed, which is fine, but i think only iab certed systems will get homebond approval.... im open to correction on this...

good luck with this, your beginning a very scary but exhilarating process.... remember that you can never plan enough, but once youve made a decision, stick to it, do not change during construction, trust your instincts....
 

Syd, I'm getting quotes at the moment for various ICF suppliers in Ireland and am keeping track of who's got IAB, BBA, etc. certification. When you say "Homeband approval" is this some sort of insurance if all goes wrong or is it just another certification?

DesignChick - I would have thought ICF would be ideal for a steep slope site, i.e. basement? This is what ICF is used for in the US. Anyway just a thought.
 
Homebond is another insurance scheme. you can get the dwelling registered with homebond for a fee (think its still €300). This will then give you a 10 year defects and structural insurance. [broken link removed]

Homebond have a main rival in 'premier insurance', you can decide yourself which to go for.....
 
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