Comparative methods

[ricedf]

I have read your magazine on a number of occasions and regularly read the posts and the most frustrating thing as a non-expert, is how posts often deteriorate into an online arguement between the experts particularly about insulation and build methods. I suspect what the original poster was hoping for something helpful rather than indecipherable.

There was an article on build methods which was sketchy on the performance of the different methods and, whilst it was interesting, it didn't help in selecting a method to procede with. I know detailing is important and that windows etc make a difference but how about a couple of 'ideals' with details to give us more of a concrete basis (not a pun!) for the non-experts to work from. Help us choose the best build method or the best products for our builds!

[sydthebeat]

I have read your magazine on a number of occasions and regularly read the posts and the most frustrating thing as a non-expert, is how posts often deteriorate into an online arguement between the experts particularly about insulation and build methods. I suspect what the original poster was hoping for something helpful rather than indecipherable.

There was an article on build methods which was sketchy on the performance of the different methods and, whilst it was interesting, it didn't help in selecting a method to procede with. I know detailing is important and that windows etc make a difference but how about a couple of 'ideals' with details to give us more of a concrete basis (not a pun!) for the non-experts to work from. Help us choose the best build method or the best products for our builds!

ricedf, it must be understood that any advise on this forum is no substitute to the engagement of a suitably qualified person to advise on matters of construction.
Lots of threads seeking advice delve into the realms of indept debate because, basically, theres no such thing as a perfect system... many hav eadvantages and disadvantages.

the most important thing to consider is, whatever build method is chosen, that best practises are adhered to... this is most difficult!!!!

as a specifier i try to specify a build sytem that i think is best, but obviously my client has to pay for it, so budget is mainly the most important factor.... that generally rules out some of the 'better' systems... such as SIPS :D...

clients and builders are fixated on traditional methods of buiding such as the 310 cavity wall..... with the advancements in building regulations and building technology, this system is been shown up more and more as being inefficient. However, its what clients and builder know, so they are very slow to divert from it... therefore we have specification such as wider cavities, blown-in insulation, internal additional drylining, etc..... these are methods to 'sticky plaster' an inefficient system. But budgetry constraints generally means thats what clients go for.... so some here take the responsibility to give all sides of the argument to the poster... arguments which are indepth and scientific most of the time.

the choice of build method would directly be related to budget... however, with professional help you can achieve the best 'bang for your buck'......

again, advice here is no substitute for paid professional help...

[heinbloed]

I fully agree. There is no shoe that fits all.
Sometimes it is difficult for the paid advisor as well to answer questions that aren't asked.The more detailed a question is formulated the less answers will go down the drain.

[ricedf]

Thanks for taking the time to reply and I would agree that professional help is important. I did recently ask an energy assessor company to have a look at my plans and give me advice and found it a waste of money really as they more or less gave me info which is freely available on the internet and were unable to unaware of other systems. The problem is picking the right professional as they sometimes are not as useful as they should be!

How about as an alternative article - a piece from 3-4 professionals giving their views on how they would do their ideal build?

The point on budget is an interesting one. My own opinion is that the standard cavity construction is a poor method but all other methods come in as a lot more expensive without good evidence that they will be worth the extra investment over time and I wonder to myself why a company that is committed to selling their product wouldn't consider an economic comparison as a sales tool.

I myself have shifted from cavity with litecrete inner leaf to ICF to poroton and am still going mainly because all the experts contradict each other leaving me in the middle scratching my progressively balding head.......And that's without even considering what to do with the roof and windows!

[Archie]

Damien,

You'll get as many opinions as there are build types and products. They all have their merits and disadvantages, if there was one product which performed head and shoulders above the compeditors on all the criterea for selecting a product, then we would all agree.

The problem of providing consistent answers lies in the questions that people invariably ask. You use 'build method' as an example of a topic that results in conflicting answers. Heres an extreme example. If you were to ask a question that would have as its answer 'cavity wall with 60 PU in cavity and drylined with 37.5 composite' then the question would go as follows:

I am building a one off house in a rural location. I will be self building and used a local guy to draw up plans. The site is half an acre, well drained and as it has road frontage, I will be orientating the front elevation withh the road which runs East West, the primary elevation will face North. The plans approved for planning are for 2,600 sq ft. My Budget is €110 per square foot, I will use an oil boiler as as I got my planning before last summer the 2005 regs are in effect (C1/C2 BER). I am prepared to pay over €1,500 per annum to heat this house to 21 degrees in living rooms in winter 18 degrees in bedrooms and will be using trickle vents in windows instead of background wall vents. I will have 2 open fires. What is the most rhobust wall construction method I can build for this price using locally available labour?

The question puts no emphasis on air tightness, moisture migration, decrement delay, life cycle costs over the mortgage term, Indoor Air quality and architectural design integrity. A good decision is made by analyzing all the options under a number of criterea headings, then these criterea are given weightings. Weighting criterea is highly subjective. The above enquiry puts emphasis on capital cost and perceived rhobustness but dosent consider other important criterea.

You asked a very thorough question about ICF vs Litecrete. The answers you got varied depending on how individuals weighted various criterea. Glas put an emphasis on simplicity, Sinnerboy's main criterium was trusted methods of construction, Viking house went for thermal density, syd the beat mentions in this post 'bang for buck' and heinbold makes the same point as me though altogether more succinctly for once. You must use their experience and put together your own matrix/table. List the alternatives on the top row and include closed panel timber frame and externally insulated block on edge, list the criteria on the left row and give them a weighting based on their importance to you. Cost 10, rhobustness 8, thermal 8, simplicity 6, breathibility/Airtightness 6, moisture 4, maintainance 2. This will give you an analythical method of comparing products that allows you to factor in your perception of the importance of the judgeing criteria. I'd wager ICF comes below closed panel timber frame.

Selecting wall materials is often seen as the most important decision in building a house, however in the heel of the hunt it is a miniscule factor when the buildings performance over its lifetime is considered. Orientation, ventilation/air tightness strategy and detail design/performance specification are much more important factors. Your build type is only as good as the site operative is trained and supervised, building control is weak in Ireland and so it is the responsibility of your design professional to extract the best quality for client. The problem in this country is that most people have no faith in the architecture profession and do not understand the finiancial and quality of life benifits in employing an Architect or suitably experienced Technician. Its a sad situation when you have to pay someone to do your plans and then have to fork out more for an energy assessor to devise a bolt-on solution to rectify a half conceived scheme. Thats not a criticism of the OP, its the fault of the Architecture profession in general.

Good luck with the build, you seem to be going the right direction. PM me if you want me to cast a constructivly critical eye over the scheme.

[heinbloed]

Well said, Archie!

[td18]

In order to set up that spreadsheet (which is an excellent idea) I've listed below alternative wall constructions, would appreciate any that can be added....

a. Externally Insulated Concrete / Blockwork

b. Poroton

c. ICF - Insulated Concrete Formwork

d. Timber frame; Closed / Open

e. Cavity wall; Partial / Full fill

[Adrian Hennessy]

f steel frame

g cob

h rammed earth

i concrete frame

j adobe

[sinnerboy]

Don't forget existing walls . many are red brick or stone - rich in character and
( sorry Heinbloed ) internal insulation is the only way to thermally upgrade . Not for technical reasons but for planning regulation / preservation of historic characteristics reasons

OR

with the rich ( not ) heritage of rendered hollow block in our semi d urban sprawls - a tight budget may tend towards internal insulation

This group may itself split as follows

Existing wall dry lined with

1. composite insulated plaster board ( PUR / EPS / mineral wool (MW) ) direct fixed to wall

2. PUR / EPS / mineral wool between battens , followed by membrane + plasterboard

3. Hemp between battens followed by membrane + plasterboard

4. Erect free standing timber stud wall followed by membrane + plasterboard
and insulate stud cavities with PUR/EPS/MW/Hemp

5. Apply 50mm ( or possibly more ) lime / hemp plaster mix

Now I know some of you ( you know who you are - you don't have to put your hand up here ) would rather boil your own ears than look at internal dry lining ..... but it has to be placed "in the mix" - to see how it compares

Good luck with it TD18