Garage door threshold makeup.

[syne]

I'm just about at dpc level on an extension and am finding the garage opening to be perplexing.

 

At the moment there is a row of trench blocks across the opening,  house dpc/ffl being one block/225mm higher than the trench blocks.

 

The ffl Of the garage Is going to be 100mm less with a makeup of.

Blinding/ dpm/ 100mm insulation/ 150mm concrete.

 

Is there a standard way to detail the opening threshold? 

 

I was thinking along the lines of

insulation stops 150mm short of perimeter and the concrete is formed in front of it? With a taper away from garage?

 

But i feel I'm missing something.

 

 

 

Edited October 23, 2023 by syne

[joe90]

3 hours ago, syne said:

With a taper away from garage?

Definitely, my last workshop build, despite rubber seal on the bottom of the roller shutter door leaked water in heavy rain even with a half meter roof overhang. My latest has a slope from the door line outwards and despite no door fitted yet rain rolls away from the entrance.

[Kelvin]

Was going to ask a similar question albeit my garage is already built. My garage door is west facing. The rain was from the east over the last week. 300mm overhang from the roof. Pretty good rubber seal on the Hormann door. Mistake I made is there’s no fall from the garage door threshold. I don’t get much rain coming under the door but it’s also not 100% watertight. Definitely add a fall. I’ll need to add a threshold of some type to try and fix this. 

[saveasteading]

I perfected this over lots of industrial doors. I'm prepared to tell you though.

 

The secret is to acknowledge that seals don't work, and drains under the door cause draughts.

I asked about patenting this but they said it was too obvious.

 

Build your external wall as normal, with a door gap. Then fix a plank on the inside, up to which you lay harcore, insulation and floor slab.

Later remove plank and construct a ramp from floor level down to outside level.

Water runs down the door and onto the ramp. Wind gusts may blow some in, but the ramp wins when the gust passes.

 

First draw where the door will sit. Set the plank at least 100mm inside that.

 

You will have a cold bridge at the ramp, but it is trivial compared to the draughts under and around the door.

 

An alternative is to cast a galvanised plate inside the door, just 10mm above concrete. Then you have to close off the ends with mastic.

[saveasteading]

31 minutes ago, Kelvin said:

Pretty good rubber seal on the Hormann door. 

Not soft enough to seal over the inevitable undulations in the concrete. 

 

As a retro-solution, buy very soft, self adhesive draughts strip and apply underneath.  

Light leakage under the seal will show if it is a local or general gap, and the size of gap.

[joe90]

With my previous workshop I was going to cut a slot with angle grinder where the door seal sat and drop a galvanised plate into it protruding 5-10mm which would cure the problem.

[saveasteading]

4 hours ago, joe90 said:

protruding 5-10mm which would cure the problem.

It is an option if you can cut a straight enough slot. Where it meets the door or wall, you need mastic because the wind will blow water to the end.

[Canski]

I used HB2 kerbstones laid on their edge. They have a natural fall on them and I will set the doors to the top of this gradient. I finished the concrete to the inside edge of the kerbstone having turned the DPM vertically up the upstanding and cut it about 10 mm below the top of the concrete. 

[syne]

Thanks all.

Water ingress is likely to be a pita, the door sits at the bottom of a steep drive that opens onto a wind tunnel of a park and for my sins im looking at a sliding door.

 

I'm thinking that a reasonably sharp incline on the threshold with an wide acro drain at the lowest point of the drive should be sufficient.

 

But after seeing the many inches of water dropped by storm babbet I'm tempted to put a second acro drain on the inside of the door for extra redundancy.

 

[Kelvin]

I’ve bought a few of those expanding water barriers as a temporary flood defence for when the odd heavy rainfall is forecast. They worked perfectly for me. 

[saveasteading]

47 minutes ago, syne said:

the bottom of a steep drive 

Can you steer the majority of the water away? It doesn't always need a fancy drain, just  a sleeping policeman on an angle. Tarmac/ stone / whatever.

Could be a dip rather than a bump, or even a dip followed by a bump, for extremes.

It then needs somewhere to go of course.

Thus the water  reaching the garage is vastly reduced and the ramp and/ or threshold should cope.

[syne]

This is how it is at the moment

 

Please forgive the brickwork.

Edited October 24, 2023 by syne

[saveasteading]

That looks good. The rain should disappear  through the gravel. Nicely sized jaggy gravel too. Make sure it is just above the grids or the plastic will chip off.

[ProDave]

My take on garage doors, is there is absolutely no need to have the blockwork across the opening.  I did not even dig the foundation trench across the opening and waste concrete filling it up.  BC did raise an eyebrow but accepted this.

 

Then the concrete floor of the garage extended out to level with the outer edge of the wall.  I have a roller door and the rubber seal at the bottom does a good job of stopping any blown rain entering. Though a bit of foresight and that portion could have been sloped.

 

We too have a drive that slopes down to the garage and have an aco drain across the front.  That is set slightly lower than the garage slab so a small step up into the garage.

 

All performed well in the recent storm and heavy rain, the drain coped well and no water in the garage.  I am glad we had the tarmac done before this recent storm, in a previous storm when it was just the MOT1 and some gravel, a lot of that got washed away.

[syne]

The grids are temporary, how permeable is resin bound?

It used to be concrete and angled toward the street. But it's now 1200mm lower and directly under the blockwork is a single sheet of rock that spans the whole site.

 

The trench blocks were put in just in case some future person wants a strange diamond shaped garage conversion. Not me ill hasten to add!

 

Edited October 24, 2023 by syne

[saveasteading]

26 minutes ago, syne said:

The grids are temporary

They don't need to be, unless you got pedestrian grade.

I've put in hundreds of m2. They wear and chip over years but are good for cars.

And they solve your water concern.

And they satisfy building regs for paved drives.

 

Not a fan of resin bound except they can look nice on patios.  

Whatever surface, the strength depends on what is under it.

 

[syne]

It was lovely and smooth and neat when they went in, took the weight of cars and vans fine.

Then the grab lorries and the concrete mixer have made it look like an old mattress. 

 

[saveasteading]

17 minutes ago, syne said:

look like an old mattress.

A good job it wasn't expensive resin then as it would be wrecked.

To get it level, hook under the grid where it is low and jiggle it gently  up to level.

A nail bar or claw hammer etc.

Gravel will migrate under it, so needs to be replaced. 

Repeat for 10 years.

 

About the drainage, are you aware of the porosity or soakaway rules for new drives? Currently you have satisfied them.

[syne]

The grids are getting taken up, and put down again once the conc slab is poured and the blocks have been dropped off.

 

Bit in a years time (hopefully just a year) when the driveway is all  landscaped I want something more permanent and decorative. 

Not sure what yet there's a thousand other design decisions in front of the drive. 🤔