Timber frame supplier decision time!

[zzPaulzz]

Hi.  We have planning approval for a two story new build in Suffolk with a treated floor area of 200-189 m2 depending on wall thickness.  I need your help to pick a TF supplier please! My shortlist is MBC Twin Wall, MBC Hi Performance, or a KTS Ultima system.  I want U of 0.12 and 0.6ACH with minimal thermal bridging so I've discounted suppliers that can't provide thermal modelling to evidence the performance of their systems.  I did look at ScotFrame but they were stupidly expensive. 

1. KTS Ultima 140/55 has some thermal bridging issues around windows and a lot of on-site work for others to complete the insulation and air tightness layers. I'm estimating £15k in labour and materials to get down to the PH 0.6ACH standard. My amateur PHPP calculations indicates the building can't quite reach Passive House standard.
2. MBC High Performance is very similar but has slightly worse thermal bridging issue around windows. They leave much less work on site for others to complete. MBC say they usually get down to 1.5ACH, so I'm estimating £6k to get to 0.6ACH (using Aero Barrier). The PHPP calculations indicates the building can just reach the Passive House standard. The MBC quote then works out £19k more than KTS to meet my requirements.
3. MBC Passive is a twin wall system with almost no thermal bridging and comes with a 0.6ACH guarantee for the finished structure before first fix.  It also uses cellulose insulation so has a much lower embodied carbon. The wall are thicker through (500mm) so the floor area drops to 189 m2.  The PHPP calculations indicates the building can meet the Passive House standard. The MBC quote was £33k more than KTS to meet my requirements.

My heart is saying go with MBC Passive. My budget says maybe KTS.  

There are other factors in play of course, such as reputation of the supplier and their customer service.  What do you think?

[Dunc]

How much effort/time do you want to put in? If you have plenty of these, pretty much any standard construction technique can be made passive. Are you sure that you/your contractor can do the airtightness work well?

If you want it wind & watertight & near-passive as fast as possible the MBC twinwall seems a no-brainer.

 

I don't really see how either the KTS or the MBC HP "systems" are different from any other 140mm stud timber frame; they're just variations on the same theme you could achieve using a stick build on site or purchase from a variety of other suppliers and they will all need significant design detailing and on-site airtightness work.

 

I would expect the floor area as drawn in the initial design reflects the INTERNAL wall (plasterboard). When your frame supplier draws up their plans they build outwards from that so your usable floor area stays the same, but your foundation footprint gets bigger for the MBC twinwall.

[zzPaulzz]

2 minutes ago, Dunc said:

How much effort/time do you want to put in? If you have plenty of these, pretty much any standard construction technique can be made passive. Are you sure that you/your contractor can do the airtightness work well?

If you want it wind & watertight & near-passive as fast as possible the MBC twinwall seems a no-brainer.

Absolutely.  Looks like we will be building through the winter so we want to get to wind & water tight ASAP. 

2 minutes ago, Dunc said:

I don't really see how either the KTS or the MBC HP "systems" are different from any other 140mm stud timber frame; they're just variations on the same theme you could achieve using a stick build on site or purchase from a variety of other suppliers and they will all need significant design detailing and on-site airtightness work.

Yes, no different.  KTS seems to use a timber I beam for the window lintel which performs better than MBC's three-stud lintel.  MBC use their TW blown cellulose frame for the roof on their Hi Performance system so much less work left to us to cover. 

2 minutes ago, Dunc said:

 

I would expect the floor area as drawn in the initial design reflects the INTERNAL wall (plasterboard). When your frame supplier draws up their plans they build outwards from that so your usable floor area stays the same, but your foundation footprint gets bigger for the MBC twinwall.

Sadly that's not the case as the external footprint is set by the planning approval so we have to work in from there.  Our planning app site layout was done assuming 500mm walls so the internal space is still generous for a three-bed. 

[G and J]

50 minutes ago, zzPaulzz said:

the external footprint is set by the planning approval

You bet it is.  I can confirm that if one’s initial assumptions are of too narrow a wall thickness then many hours are spent boiling one’s brain and an enormous quantity of scrap paper is produced.   At least we’ve now got a good supply of stuff to start fires with this autumn.  😕 

[LnP]

We're also currently comparing timber frame quotes but are not quite at the point of being able give comparitive numbers. The scopes are all different, so as you mention, it involves estimating the value of the differences. As well as Potton (KTS) and MBC, we're also looking at Fleming and Frame Technologies. Your numbers confirm how it's looking for us though, that Potton are cheaper than MBC for the frame. Additionally, MBC look expensive for the windows, assuming we would get them from the frame supplier.

 

We'd like the frame supplier to do building regs for the whole project. We have an architect, but splitting BR between the frame supplier (who logically should provide the required information for the frame) and the architect for the rest, creates an interface I'd prefer to avoid. Potton will do that. I'm not sure about MBC.

 

@zzPaulzzHave you talked to the frame suppliers about CDM roles yet? I'm planning to self manage which means I'll be Principal Contractor. I'm comfortable with that but the MBC sales manager gave strong advice against it, unnecessarily so in my opinion. That would mean engaging a main contractor, which I'm not planning to do. Also, Potton  are the only ones of the four we're talking to who are prepared to take on the role of Principal Designer. In my opinion, the frame supplier, especially if they're doing BR for the whole project, are the only sensible choice for the PD role.

[JohnMo]

11 minutes ago, LnP said:

I'm planning to self manage which means I'll be Principal Contractor. I'm comfortable with that but the MBC sales manager gave strong advice against it, unnecessarily so in my opinion

It not that difficult, I did the same.

 

For those not aware, some info from the HSE website.

 

"Principal contractor - A contractor appointed by the client to manage the construction phase on projects with more than one contractor. The principal contractor's main duty is to plan, manage, monitor and coordinate health and safety during this phase, when all construction work takes place"

 

It also says

"domestic clients have construction work carried out for them but not in connection with any business – usually work done on their own home or the home of a family member. CDM 2015 does not require domestic clients to carry out client duties as these normally pass to other dutyholders."

 

You are simply passing the duty of the Principal Contractor to yourself.

 

The bit the contractor tries not to do. "Their main duty is to plan, manage and monitor the work under their control in a way that ensures the health and safety of anyone it might affect (including members of the public). Contractors work under the control of the principal contractor"

 

Basically the Contractor is responsible for everything are engaged to do. But while on site report to the Principal Contractor.

[zzPaulzz]

1 hour ago, LnP said:

As well as Potton (KTS) and MBC, we're also looking at Fleming and Frame Technologies. Your numbers confirm how it's looking for us though, that Potton are cheaper than MBC for the frame. Additionally, MBC look expensive for the windows, assuming we would get them from the frame supplier.

Frame were even more expensive than MBC for us.  Fleming couldn’t supply thermal modelling of their system and left a lot of work to others to finish for my tastes.  

1 hour ago, LnP said:

 

We'd like the frame supplier to do building regs for the whole project. We have an architect, but splitting BR between the frame supplier (who logically should provide the required information for the frame) and the architect for the rest, creates an interface I'd prefer to avoid. Potton will do that. I'm not sure about MBC.

Our architect is doing the building regs.  They will incorporate the details from our SE (foundations) and the TF supplier.  

1 hour ago, LnP said:

 

@zzPaulzzHave you talked to the frame suppliers about CDM roles yet? I'm planning to self manage which means I'll be Principal Contractor. I'm comfortable with that but the MBC sales manager gave strong advice against it, unnecessarily so in my opinion. That would mean engaging a main contractor, which I'm not planning to do. Also, Potton  are the only ones of the four we're talking to who are prepared to take on the role of Principal Designer. In my opinion, the frame supplier, especially if they're doing BR for the whole project, are the only sensible choice for the PD role.

I have. My KTS quote stated they will be the designer for their part, but NOT the PC or the PD for the whole build.  I think Potton, sister company to KTS might do more perhaps?  I’ve discussed my approach to CDM here: 

 

[zzPaulzz]

46 minutes ago, JohnMo said:

It not that difficult, I did the same.

 

For those not aware, some info from the HSE website.

 

"Principal contractor - A contractor appointed by the client to manage the construction phase on projects with more than one contractor. The principal contractor's main duty is to plan, manage, monitor and coordinate health and safety during this phase, when all construction work takes place"

 

It also says

"domestic clients have construction work carried out for them but not in connection with any business – usually work done on their own home or the home of a family member. CDM 2015 does not require domestic clients to carry out client duties as these normally pass to other dutyholders."

 

You are simply passing the duty of the Principal Contractor to yourself.

 

The bit the contractor tries not to do. "Their main duty is to plan, manage and monitor the work under their control in a way that ensures the health and safety of anyone it might affect (including members of the public). Contractors work under the control of the principal contractor"

 

Basically the Contractor is responsible for everything are engaged to do. But while on site report to the Principal Contractor.

Agree. I feel happier about my duties there now I’m covering off the PD role with SafeScope. 

[Alan Ambrose]

Call me dumb, but the PD won’t actually be designing anything in that case?

[zzPaulzz]

Correct  The PD’s role is to consider the safety risks of every design decision and mitigate them. It is not to lead the design - that’s the architect’s job.  

[LnP]

I'm wondering if the PD role is another example where CDM 2015 isn't really a good fit for self builders, although the legal duties apply. I've not been through this process yet and maybe somebody who's seen how it works in practice can comment. But the selfbuildportal.org.uk says that PDs:

   "Plan, manage, monitor and coordinate health and safety in the pre-construction phase of a project. This includes:

• identifying, eliminating or controlling foreseeable risks;
• ensuring designers carry out their duties."

What authority does a third party PD have over e.g a timber frame designer? Or are they just mail boxing the pre-construction information into the Health and Safety File and passing it along to the client/PC? In which case maybe a client could appoint themselves as PD and do just as good a job ... and save another bill for professional services!

Edited September 9 by LnP

[shuff27]

KTS is part of the Kingspan Group: "Kingspan was dishonest and cynical, Grenfell Inquiry finds" https://www.bbc.co.uk/news/articles/clyne526506o

 

 

[zzPaulzz]

7 hours ago, LnP said:

Or are they just mail boxing the pre-construction information into the Health and Safety File and passing it along to the client/PC? In which case maybe a client could appoint themselves as PD and do just as good a job ... and save another bill for professional services!

I suspect that's exactly what they do. Mind you, a big part of ensuring safe design and practices is knowing what might go wrong and what questions to ask. That requires experience that I don't have so. If I could find a decent project manager who will work for a fee instead of wanting add a margin to all the works they procure for me then I'd lean on them. But I can't   

[zzPaulzz]

26 minutes ago, shuff27 said:

KTS is part of the Kingspan Group: "Kingspan was dishonest and cynical, Grenfell Inquiry finds" https://www.bbc.co.uk/news/articles/clyne526506o

Yep. This is another factor.  No one is perfect but corporate culture is hard to change. 

[LnP]

3 hours ago, shuff27 said:

KTS is part of the Kingspan Group: "Kingspan was dishonest and cynical, Grenfell Inquiry finds" https://www.bbc.co.uk/news/articles/clyne526506o

 

 

Interesting ... but do you think this is something to be considered in the purchasing decision for a timber frame kit?

[zzPaulzz]

37 minutes ago, LnP said:

Interesting ... but do you think this is something to be considered in the purchasing decision for a timber frame kit?

Twenty years from now I don't think so. But it's got me thinking about the embodied carbon in their products. 

[ChrisInKent]

17 hours ago, zzPaulzz said:

Frame were even more expensive than MBC for us.  Fleming couldn’t supply thermal modelling of their system and left a lot of work to others to finish for my tastes.  

Our architect is doing the building regs.  They will incorporate the details from our SE (foundations) and the TF supplier.  

I have. My KTS quote stated they ill be the designer for their part, but NOT the PC or the PD for the whole build.  I think Potton, sister company to KTS might do more perhaps?  I’ve discussed my approach to CDM here: 

You can alter the roles throughout

the process, appoint TF company as PD and PC while they are onsite doing their design & erection bit, groundworker company before that and then appoint yourself. Depends whether you are able to coordinate risk and process. We know our building better than the others do so will take roles on once they’ve left site.

 

[JohnMo]

4 hours ago, LnP said:

Interesting ... but do you think this is something to be considered in the purchasing decision for a timber frame kit?

Yep

I walked away from a kit supplier for a lot less part way through the design.

 

Open and honest is all you can hope for, anything less...

[overthehill]

23 hours ago, LnP said:

We're also currently comparing timber frame quotes but are not quite at the point of being able give comparitive numbers. The scopes are all different, so as you mention, it involves estimating the value of the differences. As well as Potton (KTS) and MBC, we're also looking at Fleming and Frame Technologies. Your numbers confirm how it's looking for us though, that Potton are cheaper than MBC for the frame. Additionally, MBC look expensive for the windows, assuming we would get them from the frame supplier.

 

We'd like the frame supplier to do building regs for the whole project. We have an architect, but splitting BR between the frame supplier (who logically should provide the required information for the frame) and the architect for the rest, creates an interface I'd prefer to avoid. Potton will do that. I'm not sure about MBC.

 

@zzPaulzzHave you talked to the frame suppliers about CDM roles yet? I'm planning to self manage which means I'll be Principal Contractor. I'm comfortable with that but the MBC sales manager gave strong advice against it, unnecessarily so in my opinion. That would mean engaging a main contractor, which I'm not planning to do. Also, Potton  are the only ones of the four we're talking to who are prepared to take on the role of Principal Designer. In my opinion, the frame supplier, especially if they're doing BR for the whole project, are the only sensible choice for the PD role.

Hi, we are building with a timber frame Fleming are providing, doing building regs and erecting, Ive been really impressed with them throughout so do take a look at them again, I also looked at Potton who were much more expensive than Fleming. We are aiming for near passive standard. We are in Cheshire, a bit further on in the process to you but have been and are going through very similar thoughts. We are managing trades ourselves after Fleming have left site and are navigating the PD role with Fleming. It is worth asking Potton if they remain the PD once their bit is done all the way to the end of the project, Im guessing they don't. We think we have found a way through with it but its been a steep learning curve, you prob have more building experience than us

[LnP]

10 minutes ago, overthehill said:

Hi, we are building with a timber frame Fleming are providing, doing building regs and erecting, Ive been really impressed with them throughout so do take a look at them again, I also looked at Potton who were much more expensive than Fleming. We are aiming for near passive standard. We are in Cheshire, a bit further on in the process to you but have been and are going through very similar thoughts. We are managing trades ourselves after Fleming have left site and are navigating the PD role with Fleming. It is worth asking Potton if they remain the PD once their bit is done all the way to the end of the project, Im guessing they don't. We think we have found a way through with it but its been a steep learning curve, you prob have more building experience than us

Very interesting thanks. I'd assumed there wouldn't be much more for the PD to do after they'd handed over the Health & Safety File and you'd prepared the Construction Phase Plan. What ongoing involvement are you seeing for the PD?

 

Perhaps you could expand on your way through on the learning curve.

 

No, I don't have much building experience!! Learning a lot though on here and as I discover new things I have to read and figure out.

[zzPaulzz]

31 minutes ago, overthehill said:

I also looked at Potton who were much more expensive than Fleming

I’m finding the opposite. Fleming’s quote was almost 50% more than KTS/Potton. However I’m finding Potton very hard to pin down to one price. They keep presenting a low base price with options that aren’t actually optional. Like the roof insulation. 

[overthehill]

On 10/09/2024 at 19:38, LnP said:

Very interesting thanks. I'd assumed there wouldn't be much more for the PD to do after they'd handed over the Health & Safety File and you'd prepared the Construction Phase Plan. What ongoing involvement are you seeing for the PD?

 

Perhaps you could expand on your way through on the learning curve.

 

No, I don't have much building experience!! Learning a lot though on here and as I discover new things I have to read and figure out.

I probably made that sound more dramatic that it was meant too! The learning curve of figuring out what we needed to do with H&S when we didnt have a main contractor involved, we've done the pre-constriction plan, risk register, started the H&S file and construction phase plan we will have to decide who will be the 'main contractor' on site if we have a few trades at once but otherwise its just keeping on top of the H&S stuff as we go along. We had quotes for the PD role but after looking into it, as long as you are on top of it, doesnt appear to be something that cant be done yourself, others may tell me Im wrong though and I will look on here at CDM threads to make sure its the right way to go. 

[overthehill]

On 10/09/2024 at 19:57, zzPaulzz said:

I’m finding the opposite. Fleming’s quote was almost 50% more than KTS/Potton. However I’m finding Potton very hard to pin down to one price. They keep presenting a low base price with options that aren’t actually optional. Like the roof insulation. 

maybe its the design that makes the difference, we didnt really have Fleming in mind at first but thought we would use the free design service to get some ideas and ended up liking working with them so stuck with it.

 

they have been very hot on keeping the design within the budget we gave them, even when we made the house bigger and wanted other changes they let us know straight away this would push our costs up and roughly how much, so Ive felt comfortable that we are in charge of the costs (as much as we can be)

 

In the past we have worked with an architect on a renovation design and had no sense at all how much it was going to cost even when we gave them a budget, when we actually got quotes we realised we couldnt afford to do it so wasted money on the design. I didnt want to be in that position again.

 

A friend of a friend used Potton so we had a look around their house, looked very nice and good quality so Im sure they would deliver a nice house. We also went and had a look at a Fleming house that was half built, also looked very good. Its so hard to choose between companies, if you can get out and look at half built or completed houses that might help

[LnP]

6 hours ago, overthehill said:

I probably made that sound more dramatic that it was meant too! The learning curve of figuring out what we needed to do with H&S when we didnt have a main contractor involved, we've done the pre-constriction plan, risk register, started the H&S file and construction phase plan we will have to decide who will be the 'main contractor' on site if we have a few trades at once but otherwise its just keeping on top of the H&S stuff as we go along. We had quotes for the PD role but after looking into it, as long as you are on top of it, doesnt appear to be something that cant be done yourself, others may tell me Im wrong though and I will look on here at CDM threads to make sure its the right way to go. 

Sounds like you have things well in hand.

 

Regarding the Principal Designer role, I've come to the conclusion that in the timber frame self build world, very few clients appoint one. I had a conversation with the operations director of a timber frame company and asked him, how many of their clients did he think appointed a PD. He said less than 5%. Bear in mind that according to the guidance, a PD should be engaging with the timber frame Designer, and the Designer would send the pre construction information to the PD to put in the H&S file. Meetings between timber frame Designers and PDs apparently just don't happen. If there was a PD, the timber frame Designer would know about it. If it's a self managed project, the vast majority of his clients are apparently taking care of the PD role themselves.

 

If anybody on here has gone through a project with a third party PD I'd be interested to hear if they thought it was helpful, i.e. did it do any more than tick a CDM box. My suspicion is that it's possibly just another cheque to write for a professional service that doesn't add value. All a third party PD will do is collect the pre-construction information into the H&S file and forward it to the client. A self managing client can do it themselves.

 

I'm not sure what you mean by, "we will have to decide who will be the 'main contractor' on site if we have a few trades at once". According to the HSE, if you the Client are self managing, it's the Client's responsibility to comply with Part 4 of the CDM regs. It's as good as saying the Client is the Principal Contractor. If your groundworker is digging a hole for a sewer chamber, it's the self managing Client's responsibility to ensure his plumber doesn't fall down it (Reg 22, Excavatiions, which is in Part 4). The groundworker won't be responsible for that.

 

Btw, I think most diligent, self managing clients will naturally take all this on. It's not onerous and just about trying to run a safe project.

[zzPaulzz]

On 09/09/2024 at 08:39, zzPaulzz said:

Hi.  We have planning approval for a two story new build in Suffolk with a treated floor area of 200-189 m2 depending on wall thickness.  I need your help to pick a TF supplier please! My shortlist is MBC Twin Wall, MBC Hi Performance, or a KTS Ultima system.  I want U of 0.12 and 0.6ACH with minimal thermal bridging so I've discounted suppliers that can't provide thermal modelling to evidence the performance of their systems.  I did look at ScotFrame but they were stupidly expensive. 

1. KTS Ultima 140/55 has some thermal bridging issues around windows and a lot of on-site work for others to complete the insulation and air tightness layers. I'm estimating £15k in labour and materials to get down to the PH 0.6ACH standard. My amateur PHPP calculations indicates the building can't quite reach Passive House standard.
2. MBC High Performance is very similar but has slightly worse thermal bridging issue around windows. They leave much less work on site for others to complete. MBC say they usually get down to 1.5ACH, so I'm estimating £6k to get to 0.6ACH (using Aero Barrier). The PHPP calculations indicates the building can just reach the Passive House standard. The MBC quote then works out £19k more than KTS to meet my requirements.
3. MBC Passive is a twin wall system with almost no thermal bridging and comes with a 0.6ACH guarantee for the finished structure before first fix.  It also uses cellulose insulation so has a much lower embodied carbon. The wall are thicker through (500mm) so the floor area drops to 189 m2.  The PHPP calculations indicates the building can meet the Passive House standard. The MBC quote was £33k more than KTS to meet my requirements.

My heart is saying go with MBC Passive. My budget says maybe KTS.  

There are other factors in play of course, such as reputation of the supplier and their customer service.  What do you think?

FYI, I have decided to go with MBC's Passive system.  Yes, there is a premium, but once I started digging into the details of other offers the list of uncovered work got longer and longer.  For me, the lack of thermal bridging and the promise of an insulated, air-tight, wind and weather-tight finished frame justified the premium. Just.