A detail for a Threshold?? with min Therm bridge

Tim Toolman

I am looking for a threshold that cuts out most of the thermal bridge that occurs, the technical guidance documents don't show any details around door entrances, maybe they're avoiding this area. Any help would be great..

BryanF

Tim Toolman wrote: »

I am looking for a threshold that cuts out most of the thermal bridge that occurs, the technical guidance documents don't show any details around door entrances, maybe they're avoiding this area. Any help would be great..

A decent arch will do this for you.

Tim Toolman

A decent arch will do this for you.

What do you mean by a decent arch??

sinnerboy

The threshold is a very difficult detail to make thermal bridge free. I have yet to see it done well myself. See here for one that is technically good if not pretty

fatty pang

sinnerboy wrote: »

The threshold is a very difficult detail to make thermal bridge free. I have yet to see it done well myself. See here for one that is technically good if not pretty

Technically good ??
Its hardly wheelchair compliant for starters.
Best I have seen is here (pages 5-8). It may not completely satisfy the THERM fetishists but its designed for severe exposure conditions which sadly is not quite as fashionable or sexy as Passiv Haus.

Poor Uncle Tom

fatty pang wrote: »

Technically good ??
Its hardly wheelchair compliant for starters.
Best I have seen is here (pages 5-8). It may not completely satisfy the THERM fetishists but its designed for severe exposure conditions which sadly is not quite as fashionable or sexy as Passiv Haus.

For your threshold details, you have filler pieces below GL with one side against the warm inside and the other side against the cold outside. If those filler pieces are timber you will get rot, if they are not timber what material are they.

Also there is NO break in the thermal bridge in some of those.

DOCARCH

Poor Uncle Tom wrote: »

Also there is NO break in the thermal bridge in some of those.

Agreed, appears to be a thermal bridge in all those details!

Threshold detail is one of the hardest details to get right and even when it is detailed right even harder to build right and needs careful watching of builders on site.

Tim Toolman

It may not completely satisfy the THERM fetishists but its designed for severe exposure conditions which sadly is not quite as fashionable or sexy as Passiv Haus.

Thanks for the suggestions, Detail 5.07 is a decent looking detail for insulation above the floor slab. Detail 5.06 with the insulation below the floor slab, the thermal break is 3 timbers?? Is it possible to order proprietary rigid insulation as filler. If this is so I would be happy with this detail.
The passive house detail is one that would be least familiar to me, it strays from the traditional Homebond detail, which i suppose when it came about first it wasn't designed with continuous thermal band as a priority. Are insulated metal cills being used, it is a good detail just so long as you don't get thrown off by the 300mm insulation in the wall. :eek:
If you google "Meeting part m and designing Lifetime homes" there are 5 or that threshold details, most of which though leave the doorframe offcentre of the wall which won't help the continuous insulation, although 4c on page 16 is probably my pick of them.

DOCARCH

Tim Toolman wrote: »

...although 4c on page 16 is probably my pick of them.

Yes, probably the best of the lot. Others all have cold bridges to a certain extent!

sinnerboy

fatty pang wrote: »

Technically good ??
Its hardly wheelchair compliant for starters.
Best I have seen is here (pages 5-8). It may not completely satisfy the THERM fetishists but its designed for severe exposure conditions which sadly is not quite as fashionable or sexy as Passiv Haus.

fatty pang

Poor Uncle Tom wrote: »

For your threshold details, you have filler pieces below GL with one side against the warm inside and the other side against the cold outside. If those filler pieces are timber you will get rot, if they are not timber what material are they.

Also there is NO break in the thermal bridge in some of those.

They're not my details. Provenance is Scottish Government - Additional common junction details, 2011. I'd be surprised if they hadn't taken the likelihood of rot into account... and I'm sure they will know what actually causes rot in timber.

fatty pang

Tim Toolman wrote: »

Thanks for the suggestions, Detail 5.07 is a decent looking detail for insulation above the floor slab. Detail 5.06 with the insulation below the floor slab, the thermal break is 3 timbers??

Its nice to see that it satisfied somebody
Whats so unsusual about using timber as a thermal break?

Tim Toolman wrote: »

Is it possible to order proprietary rigid insulation as filler. If this is so I would be happy with this detail.

See attached image (hope branding doesn't cause to much grinding of teeth) . Same company also do some very interesting structural cavity closers which I hope to see more of in lieu of the ropey wide cavity reveals I generally come across.

Tim Toolman wrote: »

If you google "Meeting part m and designing Lifetime homes" there are 5 or that threshold details, most of which though leave the doorframe offcentre of the wall which won't help the continuous insulation, although 4c on page 16 is probably my pick of them.

The publication you referenced is based on 'Accessible thresholds in new housing: Guidance for designers and builders' - a confusing document that generates more confusion. It was produced in 1998 prior to the publication of PAS23 (de facto UK performance standard for external doors). PAS23 when published noted that "Products designed to meet the requirements of Part M of the Building Regulations... are unlikely to exceed category 800x" (Watertightness 50Pa, Air permeability 200Pa) In other words the introduction of minimum standards have made that publication effectively obsolete.
Your preferred detail is not designed for a check reveal. Detail 4d is...but the bottom of the door will catch on the carpet! A check reveal is generally advisable for the Irish climate.
Good luck.

fatty pang

Glad to see a C&P mod using the tickling stick instead of the usual big shtick !

Poor Uncle Tom

fatty pang wrote: »

They're not my details. Provenance is Scottish Government - Additional common junction details, 2011. I'd be surprised if they hadn't taken the likelihood of rot into account... and I'm sure they will know what actually causes rot in timber.

Well be surprised, where there are covered, un-insulated, un-ventilated timbers below ground level you will get rot.

archtech

fatty pang wrote: »

They're not my details. Provenance is Scottish Government - Additional common junction details, 2011. I'd be surprised if they hadn't taken the likelihood of rot into account... and I'm sure they will know what actually causes rot in timber.

Its a pity that images of isotherms don't include a temperature legend.

Based on experience of using other software, the temperature looks to be sufficiently low in areas where the timber is located for condensation to occur, which in time will lead to rot.

fatty pang

Poor Uncle Tom wrote: »

Well be surprised, where there are covered, un-insulated, un-ventilated timbers below ground level you will get rot.

1. Check the position of the dpc and vapour barrier in the details.
2. Given the location of the timber elements a competent builder would be using preservative treated timber as an insurance policy. Properly set dpc/vapour barrier and moisture will not pass through.

Poor Uncle Tom

fatty pang wrote: »

1. Check the position of the dpc and vapour barrier in the details.
2. Given the location of the timber elements a competent builder would be using preservative treated timber as an insurance policy. Properly set dpc/vapour barrier and moisture will not pass through.

As stated, the timber is in the ideal location for condensation to occur at it. Condensation would provide enough moisture to rot timber. Preservative may slow the process down, but it would not stop it.

The big question is why the need for timber at all. There are propriety plastic screed stops which could be used.

Tim Toolman

fatty pang wrote: »

Whats so unsusual about using timber as a thermal break?...

I have no problem with using timber as a thermal break, but I am looking for the perfect detail. Timber does not have an adequate U-value to contribute to continuing the complete thermal wrap??. When the U-values of the walls, floors and roofs are all improving, the thermal bridge at these junctions are increasing, increasing the surface condensation at these locations.

Have a look at the following detail, drawn up with help from ye're input, and see if it would be considered sensible construction in ye're opinion...

braftery

Why not just ask your window and door supplier to give you their approved detail for your building ?

Ray Dow

fatty pang wrote: »

Technically good ??
Its hardly wheelchair compliant for starters.
Best I have seen is here (pages 5-8). It may not completely satisfy the THERM fetishists but its designed for severe exposure conditions which sadly is not quite as fashionable or sexy as Passiv Haus.

Hi, do you have a link to the full list of these details? I keep getting a 404 when i try to track them down.

The Scottish ACDs seem to be a lot more comprehensive than our own...

Eoghan Barra

fatty pang wrote: »

Glad to see a C&P mod using the tickling stick instead of the usual big shtick !

+1

hexosan

Sorry to resurrect an old thread but has anyone come up with a better way of doing the door thresholds.

BryanF

hexosan wrote: »

Sorry to resurrect an old thread but has anyone come up with a better way of doing the door thresholds.

I'd say there are a lot of architectural technicians and architects that can provide you with a perfect thermal bridge detail

fatty pang

BryanF wrote: »

I'd say there are a lot of architectural technicians and architects that can provide you with a perfect thermal bridge detail

Do you have any examples?
I've always thought its an area that designers struggle with to put it mildly. Windows - reveals and cills - in wide cavity walls are a similar nightmare for a lot of the profession, IMHO.

hexosan

BryanF wrote: »

I'd say there are a lot of architectural technicians and architects that can provide you with a perfect thermal bridge detail

Any idea of the approximate cost of getting an arch tech to draw up this detail.

galwaytt

..tbh I don't know why door manufacturers don't offer a clip-in or downstand insulated panel below their door frames as standard for this very reason.

It would be very very easy to fit a completely bridge free, rot-proof panel under any door frame.

Sandman777

I'm going to jump into this thread if that ok...

I have tricky detail on the head of a bay window in my new build where i have very little room at the window head to eliminate the thermal bridge! Basically room for a 9.5mm plaster board and maybe 10mm extra insulation!!

I came across a product mentioned in a few places called aerogel or space gel but i cant source it anywhere? It would seem the best solution if i could get it!

Is this still on the market or can anyone help with this?

Thanks
S

DOCARCH

Sandman777 wrote: »

....cant source it anywhere?

Have you tried google? Google 'spacetherm' and you may find.

Mod Note: Please no direct links to suppliers.

Sandman777

DOCARCH wrote: »

Have you tried google? Google 'spacetherm' and you may find.

Mod Note: Please no direct links to suppliers.

Ha..ha Actually very little when googled which is surprising as it sounds like a very good product! Got me thinking that it was gone off the market or was issues with it!!

fclauson

10mm if anything ain't going to be much good - you will have to re design the junction to lower the thermal bridge

The product you mention can be used BUT speak to people who have used it as it a little tricky sometimes