walter segal method

houseyhouse · 01-03-2021 6:11pm #1

Does anyone have experience with the Walter Segal method?

We're planning to extend a block-built 70s semi-d to the side and rear and to build a garden room. Construction costs are only going one way and we're not keen on taking on more debt so I'm looking into self-built options, including the Walter Segal method. I'm also very inspired by Dominic Stevens' 25k house. And I saw this extension project using Segal methods: https://www.architectsjournal.co.uk/news/konishi-gaffney-completes-52k-segal-inspired-extension

We're not builders and we don't really have any family or close friends nearby who are, but we're pretty good at DIY. We've built stud walls, built and installed kitchens, laid floors, and so on. I'm thinking we might take on the garden room first to see what the process is like. I'd love to work with an architect who's sympathetic to this approach. Any suggestions?

Thanks!

sydthebeat · 01-03-2021 6:29pm

as long as it complies with all relevant building regulations, you can build how you like.

rayjdav · 01-03-2021 7:30pm

Less than half a page into the essential method intro, it'll end up costing you more in the long run if you are not construction minded.

"Its an attitude of mind rather than a system of construction..." What????
You'll need an Engineer to simplify accepted construction methods and tradesmen to do it non standard methods €€€€€€€€€€€
Approved test results of materials out the window so you will have no industry standard paperwork to backup your methods.
"The architects role is of QS and SE...." Interesting???

Ideal concept but not practical for means of reducing construction costs imo.

Metric Tensor · 01-03-2021 7:44pm

Hi OP. The reason most extensions in Ireland are built in a roughly similar manner (with a modest level of variation in construction styles) is because that's the cheapest way of doing it. If there was a cheaper way of building it correctly you can be sure everyone would be doing it.

There's absolutely no problem doing the work yourself but if you want to do so just learn the traditional methods rather than trying to reinvent the wheel at the same time as learning how to build.

A fairly simple rule that I have never seen to be wrong. You can have any two of the following three things - but never all three:

1. A quality build
2. A speedy build
3. A cheap build

BryanF · 01-03-2021 8:17pm

I’m Familiar with Walter segal method, and have seen houses in the uk constructed using this method. I work in the construction industry and went the self-build route for my extension, in hindsight I should have borrowed and paid for a turn key, it would have been cheaper and less hassle. In my extension I went with an insulated slab, timber frame and 2ply bitumen flat roof. I’d recommend this method if you want a relatively reduced concrete, less ground works approach. Best of luck finding and arch to support your self-build, personally I wouldn’t take it on as it’s hard to price for the level of support and risk that may need to be taken on.

houseyhouse · 02-03-2021 3:47pm

Hmm. Not really the positive reaction I was hoping for!

I don't think I agree that they way it's usually done is necessarily the best/cheapest way to do it. It's what builders here are used to and so it's what they prefer. Surely if you're doing most of the labour yourself, you save a lot of money? The Segal method lets you do that relatively easily. Dominic Stevens used a lot of those techniques and built a whole 3 bed house for 25k. I'm assuming it passed all inspections etc. and I believe his house is built to near passive house standard too.

@Metric Tensor When you say better to use traditional methods, do you mean block built? My partner is from North America and they do most buildings out of timber there. He helped build a house for his uncle (who's a builder) when he was a teenager and he reckons the Segal method is quite similar to their standard stick and post building. Segal has other tricks to save money too, e.g. by building on a grid (so using full sheets of materials), not plastering internal/external walls, raising on posts to reduce concrete (which we wouldn't do) that seem like they could be incorporated into a lot of timber frame buildings.

houseyhouse · 02-03-2021 3:47pm

BryanF wrote: »

I’m Familiar with Walter segal method, and have seen houses in the uk constructed using this method. I work in the construction industry and went the self-build route for my extension, in hindsight I should have borrowed and paid for a turn key, it would have been cheaper and less hassle. In my extension I went with an insulated slab, timber frame and 2ply bitumen flat roof. I’d recommend this method if you want a relatively reduced concrete, less ground works approach. Best of luck finding and arch to support your self-build, personally I wouldn’t take it on as it’s hard to price for the level of support and risk that may need to be taken on.

I'll look into these methods. Thanks.

sydthebeat · 02-03-2021 4:43pm

houseyhouse wrote: »

Hmm. Not really the positive reaction I was hoping for!

I don't think I agree that they way it's usually done is necessarily the best/cheapest way to do it. It's what builders here are used to and so it's what they prefer. Surely if you're doing most of the labour yourself, you save a lot of money? The Segal method lets you do that relatively easily. Dominic Stevens used a lot of those techniques and built a whole 3 bed house for 25k. I'm assuming it passed all inspections etc. and I believe his house is built to near passive house standard too.

dont make too many assumptions

dominic stevens is an architect himself, so its feasible he "certified" all these works himself, as he satisfied himself that what he was doing complied with building regulations... assuming the works were certified at all.

if you are carrying out self build works, and you need the works certified by an outside agent, you need to satisfy them that the works you are carrying out complies.

do you see the difference between these two situations?

so lets look at one obstacle you are facing.
Note this is only ONE obstacle or many.

Part L of the regulations
(note im referring to the legal regulations here, not the technical guidance documents.

section 8 of SI 83 of 2019 states:

8. For new dwellings, the nearly zero energy performance requirements of this regulation shall be met by:

(a) providing that the energy performance of the building is such as to limit the calculated primary energy consumption and related carbon dioxide (CO2) to that of a nearly zero energy building within the meaning of the Directive, insofar as is reasonably practicable, when both energy consumption and carbon dioxide emissions are calculated using the Dwelling Energy Assessment Procedure (DEAP) published by the Sustainable Energy Authority of Ireland;

now, the DEAP software has very very stringent process and conventions that must be met in order for the assessment to be correct. One large issue is the thermal bridging factor of the build. Using standard details for block built houses you can use a TB factor of 0.08. When you dont use these details, and the segal method isnt included in the details, then you must use a default TB factor of 0.15.
To put that difference into perspective, assume you have an average elemental u value of the building envelope of 0.18.... which would be common enough under current regs.... when you include windows doors etc

a built with a TB factor of 0.08 will have an average elemental heat of 0.24
a built with a TB factor of 0.15 will have an average elemental heat of 0.32
now, that doesnt actually mean a 25% increase in heat loss... in reality it actually equates to a bigger increase as insulation suffers from diminishing returns the lower you get to zero.

as someone who carrys out DEAP assessments daily i can tell you its incredibly difficult to make a detached build comply to Part L and reach an A2 rating with a TB of 0.15.

so lets say you want to argue your TB factor is actually much better than 0.15. well then youd have to be able to prove that by calculations. \That means every junction of your build with need to be modelled in a specific software, assessed and measured. The professionals that do this would have to be NSAI certified and on their approved list. These services arent cheap and id imagine youd be looking at high four figures for this service. Large timber frame companies have no problem paying for these services as they can afford teh economies of scale and the repetition of their details.

also for regulation compliance you need to carry out an airtightness test and reach a certain figure. The lower the air tight result the better for energy efficiency and Part L compliance. With a DIY timber frame build like the segal method with is designed for ease of disassembly, its quite hard to ensure continuity of air tightness especially at floor junctions. expensive membranes and tapes will need to be used here, and pain staking attention to detail. All of this costs money. Wet plaster on a block face is a relatively cheap way of achieving the same result as an alternative point of view.

so theres only 2 aspects of one regulation.

thats without looking at the moisture movement in a single skin construction which needs to be detailed out... and which may require a "warm frame" type construction with insulation to the external of the structural frame. Again, costly.

You need to review Part A and determine how you are going prove its structurally stable and has the longevity required by irish building regulations. you will need to pay someone to do the structural calculations to prove your build system, using the timbers available to you, will withhold the loadings expected.

the you need to look at the feasibility of getting a single skin DIY timber frame insured? add in a flat roof and its very possible you wont get an insurer to touch it without paying a huge premium annually.

also, the methods you refer to of grids to ensure whole sheet usage etc is already used here. However the modular build we design to is to suit block sizes and courses. That allows for more a designable aspect on a 225/450 grid than an unwieldy 4"/8' grid.

in order to plan for the build, you need to first understand the law you have to build to.

Ireland has INCREDIBLY onerous and stringent building laws.

Metric Tensor · 02-03-2021 7:02pm

houseyhouse wrote: »

@Metric Tensor When you say better to use traditional methods, do you mean block built? My partner is from North America and they do most buildings out of timber there. He helped build a house for his uncle (who's a builder) when he was a teenager and he reckons the Segal method is quite similar to their standard stick and post building. Segal has other tricks to save money too, e.g. by building on a grid (so using full sheets of materials), not plastering internal/external walls, raising on posts to reduce concrete (which we wouldn't do) that seem like they could be incorporated into a lot of timber frame buildings.

I didn't say "block built" - there are plenty of timber framed buildings in Ireland constructed to incredibly high standards. These include both prefabricated timber frames and "stick built" buildings. If you investigate in detail how these timber frame houses achieve compliance with the Irish building regulations the methods are not disimilar to the methods used in many other types of construction. You still have to make them stand up, stay water tight, be safe in case of fire, prevent heat loss, be accessible to people of all abilities, etc. etc.

As a good exercise try designing the extension/building using three or four different methods. The key being to make sure you meet all the building regulations with each method - this will take quite a bit of understanding and effort. Then price up each of the four options and see where you lie. A lot of people claim they do this but a deep dive of the pricing shows that the end results don't include everything required for compliance or don't compare like with like.

Edited to add: The building regulations go from Part A to Part M. There is a "Technical Guidance Document" associated with each part showing a prima facia way of complying. Have a read through them for context. You'll see that they are fairly agnostic when it comes to what materials you use and what way you put them together provided they are of a sufficient quality and they achieve the required aims. Google TGD A, TGD B, etc.

Over time in the industry you come across many different types of construction and my experience has been that - for example - a fully compliant timber frame house, a fully compliant masonry house and a fully compliant ICF house, stack up quite close to each other in costs. I have no reason to believe that there's some magic way of building compliant buildings that is anything more than 10% different either way than the currently used methods but I'd happily be proven wrong. You meet people every day who claim their method is X amount cheaper and then when you delve into the figures in detail there's either deliberate obfuscation or simple lack of understanding.

On your point regarding "building on a grid" this makes great sense and just means less wastage - which always has been and always will be intelligent regardless of what style of construction is used. There's a wide range of good practice tips and tricks that are useful in this arena and should be followed by everyone not just to save costs but also to protect natural resources.

Nobody here is trying to "poo-poo" your ideas but if someone who had never done your job before and just read about it on the internet, without even reading the relevant rules and regulations, arrived in the door one day and told you there's a way of doing it for half the price you'd be at least a little skeptical. If it was possible to build buildings for less than half the price of everyone else a clever person would already be doing it in massive numbers across the country and making a monster profit by selling the buildings at just a little cheaper than all the other developers.

houseyhouse · 03-03-2021 1:55am

Thank you very much for all the feedback and information. You've given me a lot to think about and explore.

I really didn't mean to be rude. I wasn't trying to suggest there's a way to mass produce housing for cheaper but rather that building your own house could be cheaper if you supply a lot of the labour yourself.

Thanks again.

BryanF · 03-03-2021 9:15am

houseyhouse wrote: »

Hmm. Not really the positive reaction I was hoping for!

I don't think I agree that they way it's usually done is necessarily the best/cheapest way to do it. It's what builders here are used to and so it's what they prefer. Surely if you're doing most of the labour yourself, you save a lot of money? The Segal method lets you do that relatively easily. Dominic Stevens used a lot of those techniques and built a whole 3 bed house for 25k. I'm assuming it passed all inspections etc. and I believe his house is built to near passive house standard too.

.

You’re assuming an awful lot. Best of luck with your build.

sydthebeat · 03-03-2021 10:00am

houseyhouse wrote: »

Thank you very much for all the feedback and information. You've given me a lot to think about and explore.

I really didn't mean to be rude. I wasn't trying to suggest there's a way to mass produce housing for cheaper but rather that building your own house could be cheaper if you supply a lot of the labour yourself.

Thanks again.

supplying the labour for a conventional build will typically be cheaper

however doing anything "unconventional" such as a single skin timber construction like youre proposing will not be cheaper because you need to prove by testing and certification that your build complies.

so while the actual cost of material for the build may be less than a conventional build.... it still may end up significantly more expensive in the long run because of the ways you need to shown how you comply with irish building laws.

ireland doesnt have "trailer park" housing like America does for this reason.

Metric Tensor · 03-03-2021 11:38am

Labour is expensive so there is definitely a theoretical saving in providing your own labour in certain areas. However, that assumes that your own time is worth zero! If you're not working or have lots of free time then it could be ideal.

But at a rough guess you are looking at spending 4 times (at least) the number of hours a tradesman would to come up with a poorer quality end result. For example - if I was to tile my own bathroom it could easily take me a month trying to fit it in and out with my day job, family responsibilities, etc. I would also break a number of tiles and end up with much more wastage due to mis-cuts, etc. I'd be hopeful the end result would pass muster with herself (because she's fairly forgiving!) but there is no way it would match up to the quality of end result I'd get from a professional tiler who would be done in 2 or 3 days! If I just did a few overtime days/hours at the job I'm good at it would allow me to pay someone who is good at his/her job to do it right for me.

walter segal method

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