Being rather new to all this I was wondering ---

Would you go for timber frame (either on site or factory construction) or traditional block (or bricks, stone etc?) construction and why?

What are to cost and time implications?

... masonry IS good for thermal mass, IF you put the insulation on the outside.
'Conventional' UK builders have a problem with this concept, it seems, and so you lose part of the thermal mass if they insist on cavity construction.

For me, timber frame, with masonry internal/partition walls, and an insulated slab, for thermal mass.

Good for air-tightness, but not so forgiving when it comes to changes and amendments....

Good luck.....

Posted By: nigelTimber frame is good in winter as it warms up quickly but can overheat in summer as there is nowhere for the extra heat to go.

Doesn't sound like a problem this year in the UK by all accounts. Masonry can overheat, too, as there is nowhere for the heat to escape at night. Lived in a stone cottage in Glossop many years ago when there was a heatwave. Temperature inside got into the low 30s C and no amount of open windows at night made a difference as the 2' of stone was fully warmed up and radiating vast amounts of heat into the house at night.

A good hardwood floor can have as much thermal mass as concrete/tile (I posted figures on this ages ago). As with everything, devil is always in the details and you need skilled contractors no matter which method of construction you use. I used to think timber frame was naff when I first moved to Canada, but now I can see that it does have certain advantages - definitely a lot easier to get involved in the building process, too.

Paul in Montreal.

p.s. it was 35C here yesterday with an overnight "low" of 24C ... right now it's 34C

Steel is good, if you can cut down on the thermal bridging?
Otherwise, beware, you may be building yourself into a problem....

Good luck

... yep, fair enough.
For my own and professional interest, I would be v interested in a TI shot of the outside, in the heating season/winter.

Cheers

We've lived in a range of different construction houses over the years, from several hundred year old solid stone cottages through conventional brick and block (cavity wall) to a Scandinavian built timber frame house when we lived in Scotland.

Each has its pros and cons:

- The stone houses were cool in summer, but very slow to heat up in winter if the heating had been off for any reason. Overall they were the most comfortable during periods of very hot weather, but the high thermal mass, coupled with our lifestyle at the time (both out all day with the heating off during the colder months) meant they were pretty uncomfortable for a lot of the time in winter.

- The block and brick houses were OK, not as cool in really hot weather as the stone cottages, but a bit quicker to warm up. The only real downside was that they tended to get hot after a few days of scorching weather and then stay hot for a day or so.

- The Scandinavian (Norwegian, to be precise) timber framed house was in a very exposed location, facing west right on the west coast of Scotland. It was clad externally with rendered block and brick, with a very good (for the 1990's) thermal and airtightness spec. It had the least thermal mass of any house we've owned, and was incredibly quick to heat up after a period of being empty (less than 20 minutes in mid-winter). It was far and away the most comfortable house we've owned, and I happen to like the short thermal time constant. It was well enough insulated to not overheat in summer (although being right on the coast it did get a pretty constant breeze) and was cheap and easy to heat in winter.

FWIW I am going for a low thermal mass timber framed build, because I happen to like the way such a house responds to our changing needs. Others may prefer the stability that having a higher thermal mass gives, but my view is that this depends very much on the way you live. Even now that I'm retired I'm out of the house for several hours every day, and SWMBO is still out at work, so I have the heating off much of the time and like to be able to bring the house up to temperature quickly when needed.

Posted By: TriassicWould you go for timber frame...

Yes, that's my plan. ¹

...and why?

Mostly because it's more DIYable - I envisage getting some somebodies to do Segal style concrete pillars for me some (perhaps other) somebodies to make me a kit and perhaps assemble the heavier posts and beams on site then leave me to screw on (or up) the lighter bits and, in particularly, leave me to deal with the fiddlier airtightness issues at my own pace.

ETA: Also I like the idea that timber will sequester some carbon vs masonry which'll tend to emit it. Also timber will likely have a lower embodied energy.

¹ Though I can't help listening, somewhat wistfully, to qeipl or borpin talking about steel frames in various forms.

So if factory made timber frame is the way to go, with a nod in the direction of thermal mass using dense internal walls and maybe UFH coupled to solar, who would you buy your frame from and would they build to a design by others, or do I have to buy a standard box?

Borpin - what do you mean 'I would have used timber, but the use of insulation directly attached to the outer OSB has no precedent/accredited details....'

I thought many timber frame houses are being built with external wall insulation - you can find recommended construction details of this on nbt/kingspan/celotex/viking websites, either with render or tile clad etc?

http://www.viking-house.co.uk/selfbuilder-package.html

Posted By: DarylPA clear external wall cavity is still required to provide
ventilation to the timber frame and to provide drainage for water that may penetrate the cladding.

All the detailing I found showed the cavity *between* the insulation and the TF which defeats the object. I really did not have the stomach for a fight with the BCO to show that the risk of condensation etc was nil _and_ the risk that house insurers might baulk at the buildup. The LSF is an approved buildup already so that is why I went with it. The other reason is I was already going to use the roof system and extending it to the rest of the frame made sense.

If TRADA come up with accredited detail then it will be a no brainer as a construction method - warm wall breathing inward (as discussed at length elsewhere).

Posted By: borpin

Posted By: DarylPA clear external wall cavity is still required to provide
ventilation to the timber frame and to provide drainage for water that may penetrate the cladding.

All the detailing I found showed the cavity *between* the insulation and the TF which defeats the object. I really did not have the stomach for a fight with the BCO to show that the risk of condensation etc was nil _and_ the risk that house insurers might baulk at the buildup. The LSF is an approved buildup already so that is why I went with it. The other reason is I was already going to use the roof system and extending it to the rest of the frame made sense.

If TRADA come up with accredited detail then it will be a no brainer as a construction method - warm wall breathing inward (as discussed at length elsewhere).

I think you have mis-read the quote from the TRADA book. It imply that a cavity is required between the cladding and the insulation that is fixed directly to the outside of the timber frame, not that a cavity is needed between the insulation and timber frame, that is stupid (as you say!). BCO needs a slap!

There are details in the 5th edition of the TRADA book that show insulation on the outside of the frame (although not many). The certification comment is mainly aimed at rigid foil faced boards, giving a slight nod to breathability issues, although in a true warm wall the insulation can be vapour impermable. Warm wall is generally a good thing for timber frame (although there are still a few problems with it).

I believe I may know where the misunderstanding arose. I was somebody arguing the opposite position a while ago and at the time, Borpin and I had to disagree. At the time, it certainly appeared to me that Timber was agreeing with Borpin's position. Recently, it's become clear he doesn't.

I think the misunderstanding arose because many of the details concern insulated cladding, and I believe that is what some TRADA guidance also covers. That is, if there is insulation bonded to the external cladding (or just directly rendered insulation) then there does have to be a cavity inboard of that insulation. And that's what Borpin's examples were showing, because they were from manufacturers of such bonded systems.

But I believe that's just a special case of the fundamental rule that there has to be a cavity inboard of the cladding. Since in those cases, the insulation was bonded to the cladding, it means the cavity had to be inboard of the insulation as well. But if the insulation is separate from the cladding, the cavity can come between them. The position of the insulation relative to the timber frame is irrelevant, I think.

That's my current understanding, anyway. Hopefully I'll be put right if necessary!

djh - bang on the money.

Cavity between 'cladding' and insulation on outside of timber frame. If an insulated render system is used, there still needs to be a cavity in there, so it has to go inboard of the insulated render system, making the insualtion in the render system redundant.

If insulation is fixed to outside of the timber frame, and a separate cladding system (e.g. timber, render on backing board etc) is used with a cavity, all good.

For instance, 89 mm stud with OSB sheathing, wood fibre board insulation fixed to the outside of that, then breather membrane, timber battens then timber cladding would be fine.

The potential problems really only come when using a non breathable insulation material. Condensation is not a concern as the timber frame is all warm (and not subject to any meaningful temp gradient). The concern mainly comes from getting lots of water trapped between the insulation and timber frame. Detailing around windows is important to ensure that wind driven rain isn't pushed around the window and between the insulation and timber frame. Although the timber frame can breathe in, lots of water trapped there may cause problems. At least with breathable insulation it has two directions to make its way out. Differential movement at floor zones can also be a bit of a headache, but not a major one.

We looked at timber frame vs block when building 10 years ago. Due to the exposed location and high rainfall we went for trad. block. Didn't trust the timber frame wouldn't rot unseen for years. I just couldn't see how you could keep ALL the water out of a building in this environment - but that's just me. Did price both up and timber frame was more expensive but (supposedly) quicker. However, as a self builder I also felt that the blocks gave us more flexibility and you can leave them stood out in the rain!
Oh, and I can inspect the timbers in the roof so can satisfy my rot paranoier!

Technology has moved on since we built and there are many more build options - you'll have many hours of enjoyment deciding which one suits. But I think simple is best.