Door Threshold Detail

peterc14

The doors for my house are due to be fitted soon and just wondered what do people here recommend for the door threshold detail.

My external wall is standard 100mm block, 100mm cavity, 100mm block.

Basically when the door is fitted there will be a gap below the bottom of the door, which my builder says is fine. He said they will prop the door to fit it and then the screed for the flooring will run under the door no problem and fill the gap. Not sure how exactly this works?

The door manufacturer suggested wrapping a lintol with DPM and fitting it into the cavity so that the door would rest on this... then the screed would be place up to the lintol.

I am a bit confused and dont know the best option in relation to cold bridgin etc.

Any thoughts/opinions/suggestions welcome.

Mellor

You need to insulate the threshold so that the floor and screed are thermally separate from the external ground, steps or ramp

braftery

Ask you door manufacturer for a drawing of his recommended door threshold detail. The exact detailing will be different depending on the type of door threshold they are using and how you are finishing the building both internally and externally at this place.

Questions that need to be answered;

What does the door threshold look like ?
What is the floor build up internally ?
What is the ground level build up externally ?
if there is a step down (150mm) at the front edge of of the threshold, how is that being finished ? (ie concrete, plaster, stone ?)

Best of all ....

Get your architect/engineer to draw you a detail section drawing (using the door manufacturer threshold detail) for all your door thresholds.

Then there will be no more questions.

soldsold

Is there not a standard way to fit external doors and reduce cold bridging? Surely external doors can't all require their own bespoke solution? I'm just curious as there have been many discussions on how to fit wondows but the couple of questions raised about doors have resulted in getting the engineer to do it.

What I did was make the cavity continue under the door, make up a wbp plywood box filled with PIR insulation, close the lid, coat with fibreglass from a local boat builder to make it watertight, drop it in the cavity and foam on inside and grout of sand and cement on outside, making 100% sure it's level, and put the door on this box. Detail is from the Denny Dale passive house in Uk. Bit of work but it's perfect and cold bridge free

braftery

There are as many ways to fit doors and windows as there are methods of building houses.

The book that alot of people use in this country as the "building bible" is the Homebond book. This book offers NO solutions for door threshold details.

There are Euro Norms (EN) for window and door installation that are used throughout Europe and any deviation from them is simply not allowed.

However in Ireland, due to our governments complete lack of regulation of the Construction Industry (self policed building control .. lol), there are no norms for anything.

Door thresholds require detailing that will cover, cold bridging, water ingress and load bearing (due to traffic).

Traditional Joinery shop doors tended to be supplied without any door threshold at all, so that the builder could "figure it out later", translated to mean "not my problem".

As part of the working drawings for any building, it should be a simple thing to get a set of Entrance Door section details.

DOCARCH

braftery wrote: »

The book that alot of people use in this country as the "building bible" is the Homebond book. This book offers NO solutions for door threshold details.

That has always really surprised me! Even in revised and later editions it has not been added and its a particular area I find few builders have a clue about.

When I lived in a naughties developer built house, in winter, you could never walk in bare feet within a metre of any of the external doors for fear that your feet may freeze to the floor!

braftery

DOARCH ... and they will never add it .... why .. because would have to add another chapter !! and everyone would complain that the drawing does not show what they need for their building.

What we need is Building Regulation and Building control.

I have a door threshold manufacturer catalogue and they have an installation example section that contains 16 examples .. and I have never been able to use any of them so far.

Every single project present individual issues that need to be worked out and normally we end up drawing them up .. because upto the point when we ask the question no one has even bothered to think about it.

If I am really honest about it, this problem is much bigger than door thresholds. Most projects I work on do not have a full proper set of working drawings, that show you details (like door thresholds). Why ? because normally the services of the architect has been dispensed with prior to these happening in a bid to save money ... a seriously false economy !

PS: I am not an architect.

peterc14

Thanks for the replies.

Has anyone used a concrete lintol placed in the cavity which the door would rest on and then screed would be poured up to it? Would be interested to hear thoughts on this method...

braftery

Peter,

Are you currently at sub floor level or final screed level ?
Are you planning to have your 150mm drop at the front edge of the door threshold ?
Does the door you are buying have a sunken threshold ?

peterc14

braftery wrote: »

Peter,

Are you currently at sub floor level or final screed level ?

Are you planning to have your 150mm drop at the front edge of the door threshold ?

Does the door you are buying have a sunken threshold ?

1) At Sub Floor Level... insulation and screed will be added to take it upt to FFL.

2) Not sure waht you mean?

3) It has a low rise threshold.

braftery

A Low Rise Threshold ?

Do you have a section drawing of it ?
How does your internal floor covering meet the door threshold ?
How deep is the threshold ?
How much does the door sash over lap the threshold ?

Question 2

The internal floor level in the building will roughly 10mm under your door sash level.
This is the level at the back of the Door threshold.
What is the level at the front face of the Door Threshold ?
Is it the same as inside ?
Is it lower ?


I strongly suggest you make a section drawing of this place.

peterc14

I am confused and apologise for my lack of knowledge... I seem to have left things too late and the doors will probably be installed before I can decide the best optionn... stupid I know...

The doors will probably be installed and propped up from the sub-floor with temporary supports. Then the floor insulation and screed will be poured and run under the door (with temp supports removed)... has anyone else done this? What happens with the cavity below the btm of the door? How can you stop cold bridging?

braftery

Dont apologise and dont be confused !!

You have not left things too late ... it seems this is normal practise that these details are left until now.

If you pour concrete under the door threshold you will need to use insulation at the back of the door threshold to stop cold bridging in this place.

Get a vertical section drawing of the door including door threshold from the manufacturer.
Sketch out a vertical section of the opening as it currently exists.
Sketch in the door threshold as shown by the manufacturer.
then sketch in the rest of floor finishing details etc
work out your floor levels, water penetration and cold bridging issues on paper.

BMD

Just coming onto this now.

One question, in addition to the requirement for a thermal break (i.e., insulation) below the door threshold, should the door threshold also have a thermal break as part of its design??

braftery

Yes most decent door thresholds have a thermal break. However as the requirement is now for low access door thresholds, you will probably find that the actual threshold is pretty small and while there is a thermal break it will not be very big and usually the aluminium on the top will still cover the entire depth of the threshold.

This is one of the places where practical strength must take precedence over thermal effeciency.

Also putting insulation under the door is probably not the best solution as when people stand on the threshold you will have flex and the insulation will compress.

It is always best to sketch out a section drawing for this place from sub floor up, including all the elements from outside ground level finishes to interior floor finishes.

If you need more info PM me.

Ray Dow

braftery wrote: »

There are as many ways to fit doors and windows as there are methods of building houses.

The book that alot of people use in this country as the "building bible" is the Homebond book. This book offers NO solutions for door threshold details.

There are Euro Norms (EN) for window and door installation that are used throughout Europe and any deviation from them is simply not allowed.

However in Ireland, due to our governments complete lack of regulation of the Construction Industry (self policed building control .. lol), there are no norms for anything.

Door thresholds require detailing that will cover, cold bridging, water ingress and load bearing (due to traffic).

Traditional Joinery shop doors tended to be supplied without any door threshold at all, so that the builder could "figure it out later", translated to mean "not my problem".

As part of the working drawings for any building, it should be a simple thing to get a set of Entrance Door section details.

Hey braftery. The latest Homebond edition has a threshold detail on pg. 444. I don't know how thermally efficient it would be tho, there seems to be a serious risk of a cold bridge.

Do u know if the euro norm details you speak of are free to download?

Cheers

braftery

Ray Dow wrote: »

Hey braftery. The latest Homebond edition has a threshold detail on pg. 444. I don't know how thermally efficient it would be tho, there seems to be a serious risk of a cold bridge.

Do u know if the euro norm details you speak of are free to download?

Cheers

I have not seen the detail so I can't comment on it directly, but I can tell you that since the advent of air tight construction, it has become imperative to insure that there is no cold bridge at the door threshold or it is likely that, over time, condensation may form and pool on or close to the inside face of the threshold. Sometimes this condenstion may not be visible as it is under the final floor covering.

Standard threshold details are normally prepared by the threshold manufacturers. These can sometimes be found on the manufacturers websites.

Your window or door supplier should be able to prepare and issue threshold details specific for your site.

Ray Dow

braftery wrote: »

I have not seen the detail so I can't comment on it directly, but I can tell you that since the advent of air tight construction, it has become imperative to insure that there is no cold bridge at the door threshold or it is likely that, over time, condensation may form and pool on or close to the inside face of the threshold. Sometimes this condenstion may not be visible as it is under the final floor covering.

Standard threshold details are normally prepared by the threshold manufacturers. These can sometimes be found on the manufacturers websites.

Your window or door supplier should be able to prepare and issue threshold details specific for your site.

Thanks, I'll check them out.

The Homebond detail basically shows a concrete cill with stepped dpc behind completely crossing the cavity to finish at the inner face of blockwork.

There is an insulated upstand behind the inner block work. The proprietary threshold is shown starting above the inside face of the conc. cill. Meaning there is approx a course of blockwork between the insulated upstand and the threshold.

There is a flat transition unit shown between the upstand and the threshold resting on the inner course. I'm assuming if this transition unit offered some form of insulation it would go someway to combating the cold bridge?