Tony99

Basic advice of block construction and timber cladding please.

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After several months we are good to go with tendering our new house build and our architect is drawing up detailed plans for this....our architect is advising block construction (mainly due to familiarity, I think) rather than timber frame (which is what I was considering-mainly because that is what is most prominent at self build shows and it also seems very popular on this site!). We are planning on finishing with a timber cladding e.g. cedar/larch etc. I understand that most people building their own homes want to exceed the building regs in terms of insulation/air tightness etc. My (naive!) questions are:

What do people recommend using for the actual construction method and insulation to achieve better than building regs values?

Do we simply state in the tender that we want to achieve a value of 'x' and see what builders come back with?

If we are using timber cladding and not brick, what is generally used to form the outer leaf to attach the cladding to?

Thanks!

 

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2 minutes ago, Tony99 said:

Do we simply state in the tender that we want to achieve a value of 'x' and see what builders come back with?

 

I think it’s more a case of what your architect comes back with!

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So your looking to do a self build and from what it seems from your post you wanted to go for a timber frame but as your architect likes block your going to go that way.  It's your money paying for the build so  go and do your research and  tell him that to draw up the plans to suit your choice.  If it's timber then fine. 

Most timber frame companies will offer you certain  packages with a u value to suit your budget and a max target for  airtightness that they guarantee they will hit.  

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5 minutes ago, Declan52 said:

So your looking to do a self build and from what it seems from your post you wanted to go for a timber frame but as your architect likes block your going to go that way.  It's your money paying for the build so  go and do your research and  tell him that to draw up the plans to suit your choice.  If it's timber then fine. 

Most timber frame companies will offer you certain  packages with a u value to suit your budget and a max target for  airtightness that they guarantee they will hit.  

Thanks. Being a novice with this, I initially presumed block construction but there is far more promotion of timber frame in the magazines and forums and trade shows that I did consider this method. The research is difficult to do in an impartial/unbiased way as everyone who I speak to has their own take on things! Ultimately, one has to trust someone with advice and as our architect is very well known to us and has done some good work locally and for friends, we have taken on his advice.

As Joe 90 says, we will see what the architect comes up with!

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34 minutes ago, Tony99 said:

As Joe 90 says, we will see what the architect comes up with!

 

Let me rephrase that. It’s fir the architect to come up with a build THAT YOU WANT, if you want timber frame then tell him. What I meant about the architect was to come up with a build that meets your requirements regarding U value. I have said before on here that I believe too many architects try to get their clients to do what they want not what the client wants. With our build I wanted a brick skin and lots of heavy materials (used to be called thermal mass in the old days!). I went with brick and block fir that reason but there are some very good builds done by members on this forum in timber frame. @JSHarris for one and his blog is a very informative read that has made me understand sooo much about good building.

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To chuck another angle at it, I have recently spoken to two small developers who are both changing the way they build as they can’t get the trades to build how they are used to, for example bricklayers are calling all the shots in the south east at the moment demanding the highest pay I have ever seen. 

Would it be wise to build in block if you can’t get blocklayers 

timberframe has many plus points as well as minus points, if you are on a tight time frame I wouldn’t dream of blocks, too many things to hold you up, trades and the weather 

also you need to look at following trades

each build method is different you need to do your own research to iron out the little bits

im an ex bricklayer and I’m building in icf. 

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According to figures published in a self build magazine a few months ago, brick and block is still the preferred construction method for self build and absolutely dominates mainstream house building.

 

Three brickies in a tatty transit van do not have a marketing budget unlike those promoting alternative manufactured brand-name build methods, hence the unbalanced impression given by magazines and trade shows.

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58 minutes ago, joe90 said:

 

Let me rephrase that. It’s fir the architect to come up with a build THAT YOU WANT, if you want timber frame then tell him. What I meant about the architect was to come up with a build that meets your requirements regarding U value. I have said before on here that I believe too many architects try to get their clients to do what they want not what the client wants. With our build I wanted a brick skin and lots of heavy materials (used to be called thermal mass in the old days!). I went with brick and block fir that reason but there are some very good builds done by members on this forum in timber frame. @JSHarris for one and his blog is a very informative read that has made me understand sooo much about good building.

Yes-I get the idea of the architect doing what they want instead of listening to the paying client....tail wagging the dog!! Actually, i like the idea of high thermal mass-so block would probably be better than timber frame...our house orientation means it will be in the sun a lot, so I presume a high thermal mass may even out temp fluctuations??

And, yes I'll speak to our architect to make sure that we are factoring insulation/air tightness that exceeds the regs! I'll certainly have a look at JSHarris's blog!

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15 minutes ago, epsilonGreedy said:

According to figures published in a self build magazine a few months ago, brick and block is still the preferred construction method for self build and absolutely dominates mainstream house building.

 

Three brickies in a tatty transit van do not have a marketing budget unlike those promoting alternative manufactured brand-name build methods, hence the unbalanced impression given by magazines and trade shows.

Yup-it is easy to get swept away with all the promotion of these bigger TF companies!

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1 hour ago, Russell griffiths said:

To chuck another angle at it, I have recently spoken to two small developers who are both changing the way they build as they can’t get the trades to build how they are used to, for example bricklayers are calling all the shots in the south east at the moment demanding the highest pay I have ever seen. 

Would it be wise to build in block if you can’t get blocklayers 

timberframe has many plus points as well as minus points, if you are on a tight time frame I wouldn’t dream of blocks, too many things to hold you up, trades and the weather 

also you need to look at following trades

each build method is different you need to do your own research to iron out the little bits

im an ex bricklayer and I’m building in icf. 

I think we will get a much better idea when the tenders go out/come back...I'm not in a particular rush to build-much keener on waiting for an outfit I have confidence in! No idea what labour market is like in the East Midlands.....our build is, I think, relatively straight forward on paper i.e. very good access, level ground, fairly uncomplicated design etc so hopefully builders won't be put off!

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@Tony99 where in the country are you?, if you are near Devon and want masonry construction I can very much recommend my builder, he was brilliant (but booked up a lot, as that’s what happens when you are good!).

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24 minutes ago, Tony99 said:

Yes-I get the idea of the architect doing what they want instead of listening to the paying client....tail wagging the dog!! Actually, i like the idea of high thermal mass-so block would probably be better than timber frame...our house orientation means it will be in the sun a lot, so I presume a high thermal mass may even out temp fluctuations??

And, yes I'll speak to our architect to make sure that we are factoring insulation/air tightness that exceeds the regs! I'll certainly have a look at JSHarris's blog!

 

Might want to read this: https://forum.buildhub.org.uk/topic/16-the-great-thermal-mass-myth/ 😏

 

The key thing is really the thermal time constant and perhaps as important, choosing a high decrement delay insulation/structural build up.  Mass doesn't come into it, as internal comfort, in terms of having a house that doesn't respond rapidly to outside temperature changes (like a caravan) is dominated by the insulation decrement delay and the heat capacity and thermal conductivity of about the first 100mm of internal structure - anything deeper doesn't really do much in terms of being able to work usefully towards buffering the internal temperature.

 

Our build is timber frame, with no masonry, yet has a thermal time constant of days, very similar (but massively more thermally efficient) to an old granite cottage we owned about 30 years ago.  One consequence of this is that the heating doesn't come on very often.  Today was a bit milder than yesterday (around 7 or 8 deg C) so the heating hasn't come on at all yet.  The rooms are sitting at around 21.8 deg right now and I guess the heating may come on for an hour or so tomorrow morning, but looking at the forecast my guess is that it won't need to come on on Tuesday at all, as there should be enough heat stored, plus incidental thermal gains, to keep the house warm (above the 21.5 deg C that the thermostat is currently set to).

 

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30 minutes ago, joe90 said:

@Tony99 where in the country are you?, if you are near Devon and want masonry construction I can very much recommend my builder, he was brilliant (but booked up a lot, as that’s what happens when you are good!).

Unfortunately, we are in south Leicestershire...quite a way from you! but thanks for the offer!!

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@JSHarris

 

I am trying to understand thermal mass. Which would be better for thermal mass:

 

100mm block+100mm insulation+100mm block+50mm insulation

 

Or 100mm block+150mm insulation+100 block

 

The above layered external to internal.

 

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38 minutes ago, JSHarris said:

 

Might want to read this: https://forum.buildhub.org.uk/topic/16-the-great-thermal-mass-myth/ 😏

 

The key thing is really the thermal time constant and perhaps as important, choosing a high decrement delay insulation/structural build up.  Mass doesn't come into it, as internal comfort, in terms of having a house that doesn't respond rapidly to outside temperature changes (like a caravan) is dominated by the insulation decrement delay and the heat capacity and thermal conductivity of about the first 100mm of internal structure - anything deeper doesn't really do much in terms of being able to work usefully towards buffering the internal temperature.

 

Our build is timber frame, with no masonry, yet has a thermal time constant of days, very similar (but massively more thermally efficient) to an old granite cottage we owned about 30 years ago.  One consequence of this is that the heating doesn't come on very often.  Today was a bit milder than yesterday (around 7 or 8 deg C) so the heating hasn't come on at all yet.  The rooms are sitting at around 21.8 deg right now and I guess the heating may come on for an hour or so tomorrow morning, but looking at the forecast my guess is that it won't need to come on on Tuesday at all, as there should be enough heat stored, plus incidental thermal gains, to keep the house warm (above the 21.5 deg C that the thermostat is currently set to).

 

Thanks JS...I have just started reading your blog and have read the 'thermal mass myth' thread: I think I'll need to read it again for it to fully sink in [and I consider myself someone who understands science/physics!!]. The bit I have difficulty with is how much other factors such as how altering the size of a south or north facing window will have on how much energy one uses in the house or how constant the temp stays in the house etc.  The relative effect of multiple factors e.g. type of wall construction, insulation, house orientation, site and size of windows, use of MHRV etc is still a little lost on me! Our house has been designed to have few north and east facing windows (partly for energy purposes but also because of what we would overlook)  and bigger south and west windows. I'm starting to think that the issue we may have is not how to keep our house warm in winter, but how to keep it cool in summer (especially if we have a repeat of this summer's weather!!). I have been advised to make the house as insulated and air tight as we can afford....

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10 minutes ago, epsilonGreedy said:

@JSHarris

 

I am trying to understand thermal mass. Which would be better for thermal mass:

 

100mm block+100mm insulation+100mm block+50mm insulation

 

Or 100mm block+150mm insulation+100 block

 

The above layered external to internal.

 

 

 

There's no such thing as thermal mass, hence the problem!

 

There is a fair bit in that thread I linked to above that works through what people mean when they use the term "thermal mass", but as there are no units associated with it and no means of measuring it, my view is that "thermal mass" remains a bit of a myth.

 

The closest approximation to what people mean when they use this term is probably the thermal time constant of the house - how quickly, or slowly, it responds to changes in outside conditions.  Decrement delay is important, and this article gives a good insight into what it means in practice: http://www.greenspec.co.uk/building-design/decrement-delay/

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1 hour ago, JSHarris said:

and the heat capacity and thermal conductivity of about the first 100mm of internal structure 

 

Yes, heat capacity is a better term. I built using 100mm concrete block wet plastered as my inner skin followed by 200mm of insulation then a brick skin. The idea was for the house to stay at a constant temperature along with UFH within the concrete slab.

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3 minutes ago, Tony99 said:

Thanks JS...I have just started reading your blog and have read the 'thermal mass myth' thread: I think I'll need to read it again for it to fully sink in [and I consider myself someone who understands science/physics!!]. The bit I have difficulty with is how much other factors such as how altering the size of a south or north facing window will have on how much energy one uses in the house or how constant the temp stays in the house etc.  The relative effect of multiple factors e.g. type of wall construction, insulation, house orientation, site and size of windows, use of MHRV etc is still a little lost on me! Our house has been designed to have few north and east facing windows (partly for energy purposes but also because of what we would overlook)  and bigger south and west windows. I'm starting to think that the issue we may have is not how to keep our house warm in winter, but how to keep it cool in summer (especially if we have a repeat of this summer's weather!!). I have been advised to make the house as insulated and air tight as we can afford....

 

Summer, or more often Spring and Autumn, overheating certainly needs consideration once you start to improve the insulation and airtightness of a house.  Glazing is a mixed blessing, as the amount of heat that can come in via windows facing the sun, especially when the sun is low in the sky and so the heat penetrates more deeply into the house (hence the Autumn/Spring concerns).  We have a large South-facing triple glazed gable and designed in a large roof overhang to limit the Summer overheating potential.  However, we found that the main problems were hot days in Spring and Autumn, where the sun was low enough to come in under the shading.  We ended up adding some (very expensive) heat-reflecting film to the outside of the windows to reduce the solar gain a lot.

 

We've found that East facing windows tend to give a lot more solar gain in summer than those facing West, perhaps because on sunny days in summer the air can be clearer in the early morning, and with the sun rising well North of East there is a fair bit of time when East facing windows have a significant amount of solar gain.  By late afternoon, the air often seems to be a bit hazy, and this definitely seems to reduce the amount of solar gain from the West, as even though we have some big windows facing in that direction we don't have overheating problems in those rooms.

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31 minutes ago, JSHarris said:

 

Summer, or more often Spring and Autumn, overheating certainly needs consideration once you start to improve the insulation and airtightness of a house.  Glazing is a mixed blessing, as the amount of heat that can come in via windows facing the sun, especially when the sun is low in the sky and so the heat penetrates more deeply into the house (hence the Autumn/Spring concerns).  We have a large South-facing triple glazed gable and designed in a large roof overhang to limit the Summer overheating potential.  However, we found that the main problems were hot days in Spring and Autumn, where the sun was low enough to come in under the shading.  We ended up adding some (very expensive) heat-reflecting film to the outside of the windows to reduce the solar gain a lot.

 

We've found that East facing windows tend to give a lot more solar gain in summer than those facing West, perhaps because on sunny days in summer the air can be clearer in the early morning, and with the sun rising well North of East there is a fair bit of time when East facing windows have a significant amount of solar gain.  By late afternoon, the air often seems to be a bit hazy, and this definitely seems to reduce the amount of solar gain from the West, as even though we have some big windows facing in that direction we don't have overheating problems in those rooms.

That's interesting...we too have designed an 8ft 'overhang' at the gable end of our single storey kitchen-partly for an outside patio area that is under roof but also to reduce solar gain in summer. Seems like we may need to put some 'louvres/slats' at the top to reduce the lower sun in spring/autumn! 

I presume you felt triple glazing had significant advantages over double glazing??

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Triple glazing is significantly more comfortable than double glazing, we've found.  The difference is more than the U value would suggest, as triple glazing can have two panes with an IR reflective coating and this means that when you're sitting or standing near it on a cold day you don't feel the heat radiating out through the glazing, as your own body heat is reflected back; about twice as effectively than with double glazing and its single low e coating.  Triple glazing can have two panes with low e coating, as the coating has to be inside the sealed units, on the sides of the panes facing inwards, for protection from damage.

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@Tony99 I would've thought the architect should be drawing up plans in line with your brief i.e. if you want the house to have certain performance characteristics then he should choose a construction method which satisfies that along with any other factors e.g long spans, curves, etc which in themselves often drive a particular construction method.

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2 minutes ago, Tosh said:

@Tony99 I would've thought the architect should be drawing up plans in line with your brief i.e. if you want the house to have certain performance characteristics then he should choose a construction method which satisfies that along with any other factors e.g long spans, curves, etc which in themselves often drive a particular construction method.

Yes, you're right...I think I need to have another chat with him about this! I think my idea of whose responsibilities things are is not quite correct...

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There's nothing wrong with a preference though @Tony99. If he/she is pushing b&b simply ask why in preference to other methods. Good luck.

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