Timber Frame Pros Cons

[puntloos]

Perhaps it's worthwhile to list the Advantages/Disadvantages on timber frames somewhere. Couldn't find such a post so I'll start this one. 

 

My current impression of the Pro/Con, quickly jotted down, please correct/suggest changes and I will update, perhaps elaborate on the items a bit etc.
 

Benefits of Timber Frame:
- Faster construction once started

- Easier transport to remote sites

- Sustainable

- Accuracy of design

- Increased certainty of cost

- Lower running costs (easier to insulate)

 

Downsides of Timber Frame:

- Material Costs (compensated partially with less labour cost)

- Harder to fix calculation mistakes, or if caught short during build

- Large cash up front

- Noise between floors harder to mitigate

- Larger potential for floors to be creaky/bendy

- Harder to insert cabling/ducting in walls

- Extra work/cost needed for upstairs Underfloor Heating (fortification to carry the screed?)

Edited September 6, 2019 by puntloos

[Miek]

I would add. You need a more accurate foundation to build off as the tolerances for  a timber frame are much smaller than block for example. You need to be plumb, true and square to with in a few mm, then the timber work will be straight forward and accurate. 

[dpmiller]

Not sure I agree with many of your downsides...

If it's a factory kit, you won't be short.

Payment generally phased

no difference in floor buildup, same structural and acoustic considerations. Case in point, we've poured screed over posijoists, and while the accousitc insulation is mostly in place the PB isn't up yet. Better half clumps about in hiking boots on the site and based on the foot noise I went outside to talk to her (I could hear footfall but absolutely no indication of direction) only to find she was upstairs directly above me... Floor is both stiff and silent.

Exterior walls can be service battened.

[Jeremy Harris]

11 minutes ago, Sensus said:

On the 'cons' side, I'd add:

• Reduced thermal mass makes them more prone to overheating due to solar gain.
• Future modifications (or on-site design alterations) need to be more carefully considered.
• Attenuation of external noise is not quite so good (and depends on type of insulation used - PIR is much worse at noise, while being much better at thermal insulation than mineral wool, for example).
• More sensitive to workmanship in terms of future defects.
• Build programme has to be managed more accurately; the (accurate) slab has to be ready and waiting the day the TF is ready for delivery, for example (otherwise you may get charged storage by the manufacturer), and you ideally don't want to leave the partially completed frame exposed to the weather for very long.

 

 

I, and others, have found that some of these points may not be true. 

 

The thermal time constant of our house (and others here that have used a similar timber frame construction) is significantly longer than that for many common masonry construction houses.  The decrement delay exceeds the diurnal temperature change period, so virtually no heat from the outer skin ever makes it into the inner skin.  What solar gain issues there are come from solar gain through the glazing.  The thermal time constant for our build is over 24 hours, compared with around 3 hours for our old block and brick house, with solid concrete floors.

 

Likewise with sound insulation.  External noise is incredibly well attenuated, to the point where it feels a bit eerie inside at first.  Several here have visited our build and can confirm this, as the silence as soon as the front door is closed is something most people notice straight away.

 

Both the noise attenuation and the high decrement delay of the structure is primarily due to the use of blown cellulose insulation, I believe.

 

The main point I'd agree with is the need for accuracy when constructing the foundations.  This led us to use the same company for both the passive slab and frame, as that ensured the two mated up perfectly.  It was my greatest concern during the early stages, given the tight tolerance needed for the type of prefabricated panel timber frame we wanted to use.

[the_r_sole]

.

Edited September 26, 2019 by the_r_sole

[Jeremy Harris]

2 minutes ago, the_r_sole said:

 

Have you got some posts on your wall construction on here @JSHarris?

I'm trying to work through a blown cellulose option with a client at the moment....

 

 

There's some stuff on my blog that may be of help:

 

The passive slab: http://www.mayfly.eu/2013/10/part-sixteen-fun-and-games-in-the-mud/

 

The start of the frame erection: http://www.mayfly.eu/2013/10/part-seventeen-day-one-of-the-build/

 

The end of frame erection: http://www.mayfly.eu/2013/10/part-eighteen-a-house-in-4-12-days/

 

Blowing in the insulation: http://www.mayfly.eu/2013/11/part-twenty-one-putting-in-the-insulation/

 

The stuff I submitted to BC, which includes a section drawing: http://www.mayfly.eu/2013/09/part-fifteen-the-site-is-finally-ready/

 

[ProDave]

4 hours ago, puntloos said:

Downsides of Timber Frame:

- Material Costs (compensated partially with less labour cost)

- Harder to fix calculation mistakes, or if caught short during build

- Large cash up front

- Noise between floors harder to mitigate

- Larger potential for floors to be creaky/bendy

- Harder to insert cabling/ducting in walls

- Extra work/cost needed for upstairs Underfloor Heating (fortification to carry the screed?)

Cost. I doubt it was much different to masonry. We paid in stages in arrears, so no massive burden.

 

Why would floors be creaky and bendy?  It is normal to fit timber floors in a masonry build as well.  If they are creaky and bendy, someone has messed up on the joist calculations, and / or fitted them badly.

 

Cabling in walls is best dealt with by a service void that also ensures you don't penetrate the air tight layer.

 

Upstairs UFH can also be with spreader plates that require no fortification of the floor structure.

[nod]

I would always favour Traditional over TF

If your ever likely to sell Most buyers would prefer Traditional 

Largely due to the bad TF houses that where thrown up in the 80s

 

Cons for TF 

More expensive

Less solid feel Can be a bit creeky 

Far more settlement cracks

 

From a self builders point it’s a no brainer 

Far more pros than cons

You will Pay Far more to get to watertight   But you will have a fixed price 

Same work and timescale for drains and foundation 

But you will have a watertight house in a matter of weeks 

No weather reliance 

 

[SteamyTea]

I think most of the 'cons' go back the Barrett Homes fiasco of the late 1980's, more than 30 years ago now.

Anything that is designed and built badly is going to have problems.

It does seem that brick and block is a really English thing, most of the world uses poured concrete or timber.

A friend of mine, who is unfortunately American, worked for a large Architectural company, when I said the old saying 'as safe as bricks and mortar', she did not know what it meant.

6 hours ago, Sensus said:

Reduced thermal mass makes them more prone to overheating due to solar gain

Or the windows are too large.

[K78]

5 hours ago, nod said:

I would always favour Traditional over TF

If your ever likely to sell Most buyers would prefer Traditional 

Largely due to the bad TF houses that where thrown up in the 80s

 

Cons for TF 

More expensive

Less solid feel Can be a bit creeky 

Far more settlement cracks

 

From a self builders point it’s a no brainer 

Far more pros than cons

You will Pay Far more to get to watertight   But you will have a fixed price 

Same work and timescale for drains and foundation 

But you will have a watertight house in a matter of weeks 

No weather reliance 

 

 

 

I am planning to use block as I’m on a tight budget and prefer block for the reasons you listed. However I’m reluctantly looking back through basic timber frame quotes as I’ve been quoted between £2 ( local, dodgy builder) and £3.50 per block. 

 

At £3.50 a block I could have a basic timberframe supplied and erected for just £4K more (£19k) than labour cost of my walls. 

Edited September 6, 2019 by K78

[Patrick]

7 hours ago, Sensus said:

On the 'cons' side, I'd add:

• Reduced thermal mass makes them more prone to overheating due to solar gain.

I just have to add this

?

 

 

[puntloos]

6 minutes ago, Patrick said:

I just have to add this

?

 

Awesome JSHarris post I hadn't seen yet.

 

It's weird, instinctively we all know the "cool church in a heat wave" feel, and the "sweltering wood sauna" 

Perhaps that's the root of our biases?

 

 

[Jeremy Harris]

11 minutes ago, puntloos said:

 

Awesome JSHarris post I hadn't seen yet.

 

It's weird, instinctively we all know the "cool church in a heat wave" feel, and the "sweltering wood sauna" 

Perhaps that's the root of our biases?

 

 

 

The problem is that someone, years ago, thought that mass was what stabilised temperature in a building, most probably because massive stone buildings tend to maintain a fairly stable temperature.  Mass isn't the thing that's making the temperature stable, though, decrement delay is.  There's a useful description of decrement delay here: http://www.greenspec.co.uk/building-design/decrement-delay/

 

In relation to this thread, it's fairly easy to build a timber frame house with a long decrement delay.  One way is the way we've chosen to do it, which is to use fairly thick walls and roof, filled with blown cellulose.  Blown cellulose is much the same as timber in terms of its heat capacity for a given mass, and it holds a lot more heat per unit mass than concrete, brick or stone.  It is also a reasonably good insulator,  much better than concrete, brick or stone, so it works well at slowing down the rate at which heat flows through it, in either direction.  This slowing down is what increases the decrement delay and also increases the thermal time constant of the house, so it takes a long time for the house to cool down or heat up when conditions change.

[Ralph]

5 hours ago, nod said:

I would always favour Traditional over TF

If your ever likely to sell Most buyers would prefer Traditional 

Largely due to the bad TF houses that where thrown up in the 80s

You would be in the minority building traditionally here in Scotland though. While TF accounts for about 23 % in England it's 83% in Scotland and rising (2016 figures)

[SteamyTea]

1 minute ago, Ralph said:

While TF accounts for about 23 % in England it's 83% in Scotland and rising (2016 figures)

I suspect that the majority of TFs in England is the volume builders.  Most small developers probably stick with block.

[Jeremy Harris]

1 minute ago, Sensus said:

Yes, I've seen that.

 

I won't bother responding, as I've upset JS quite enough just recently. ?

 

For the record, I've not been upset at all.  Hopefully we can all express a view here without causing offence; we may not necessarily all agree all of the time, but then life would be pretty dull if we all did.

[Wagas]

Being half way through a brick and block build I'd have thought TF pros would be:

 

Less ordering and co-ordinating of deliveries of endless bricks, blocks, sand and cement.

Carpenters are messy but I much prefer cleaning up after them than brickies!

Less difficult waste to dispose of... excess timber can be burned, cut blocks can't 

Less time watching the skies and praying it doesn't rain

Less money spent on scaffolding but I guess this is negated if TF is much more expensive than brick and block

 

[MikeSharp01]

30 minutes ago, Wagas said:

Less money spent on scaffolding but I guess this is negated if TF is much more expensive than brick and block

I am not sure TF is more expensive than brick and block once you do a fuller cost accounting exercise and its all timber rather than brick skinned timber frame. 

[Thedreamer]

18 hours ago, puntloos said:

Perhaps it's worthwhile to list the Advantages/Disadvantages on timber frames somewhere. Couldn't find such a post so I'll start this one. 

 

My current impression of the Pro/Con, quickly jotted down, please correct/suggest changes and I will update, perhaps elaborate on the items a bit etc.
 

Benefits of Timber Frame:
- Faster construction once started

- Easier transport to remote sites

- Sustainable

- Accuracy of design

- Increased certainty of cost

- Lower running costs (easier to insulate)

 

Downsides of Timber Frame:

- Material Costs (compensated partially with less labour cost)

- Harder to fix calculation mistakes, or if caught short during build

- Large cash up front

- Noise between floors harder to mitigate

- Larger potential for floors to be creaky/bendy

- Harder to insert cabling/ducting in walls

- Extra work/cost needed for upstairs Underfloor Heating (fortification to carry the screed?)

 

Others have already commented on many of the points I would make.

 

My only point would be timber framing can cover a broad range of building techniques.

 

As example our timber frame was cut and erected on site by two experienced joiners. 

[Jeremy Harris]

3 minutes ago, Sensus said:

Suffice to say that I will be continuing to use the term 'thermal mass', and so do consciously and advisedly. ?

 

Out of interest, what units do you use to measure "thermal mass", to enable one form of construction to be assessed against another as having more, or less, of it?

[SteamyTea]

34 minutes ago, Sensus said:

Too large says who?

Too large to maintain temperature stability.

30 minutes ago, JSHarris said:

Out of interest, what units do you use to measure "thermal mass"

Good question, look forward to the answers

[ProDave]

23 hours ago, nod said:

I would always favour Traditional over TF

If your ever likely to sell Most buyers would prefer Traditional 

Largely due to the bad TF houses that where thrown up in the 80s

 

Cons for TF 

More expensive

Less solid feel Can be a bit creeky 

Far more settlement cracks

 

It depends where you live.  I agree, in the SE of England, most buyers do favour "solid" and as you say because of some shockingly badly built early TF houses that they just can't get out of their minds.

 

Ask the same question in Scotland and TF is considered normal and has been for some time.

 

I Don't recognise those defects of creaky and settlement cracks, not in any TF house I have seen up here.

[SteamyTea]

49 minutes ago, Sensus said:

that's wrong, not the glazed area.

So do you think that is what really happens.

If you had a fixed structure size, and a fixed window area, with the only thing changing is the mass of the building, then temperatures would be significantly different for varying weather conditions and climate regimes?

[SteamyTea]

OK

So I have wasted 3 years at university studying this, plus ten years thinking about it, and the last 2 years testing it.

Can you show me the significant difference in these two charts.

 

[nod]

3 minutes ago, ProDave said:

It depends where you live.  I agree, in the SE of England, most buyers do favour "solid" and as you say because of some shockingly badly built early TF houses that they just can't get out of their minds.

 

Ask the same question in Scotland and TF is considered normal and has been for some time.

 

I Don't recognise those defects of creaky and settlement cracks, not in any TF house I have seen up here.

I frame and plaster quite a bit of TF Mostly student accommodation 

Its normal to have a 5 % retention 

The retention isn’t taken for TF 

We are paid to go back several times to sort out the cracks