ᐅ Construction of a screed garage floor with spot heating using electric underfloor heating
Created on: 22 Jul 2019 15:38
P
Patkia
Hello everyone,
I am currently researching garage floors and wanted to ask my question here.
The garage is attached to the house, and the floor slab was poured together with the one for the house. It is a foundation slab made of waterproof concrete, reinforced with steel mesh (WU) C 25/30, serving as a load-bearing element with an encircling frost skirt made of steel fiber concrete C 25/30 (0.80 x 0.30 m (2 ft 7 in x 1 ft)), without additional insulation.
There is about 6.30 m (21 ft) of space in front for cars and about 2.15 m (7 ft) at the back for a workshop/storage area.
The garage is not intended for permanent occupancy, but I want to be able to work on my car or motorcycle in winter without freezing my feet or kidneys while lying on the floor. Therefore, I would like to include electric underfloor heating when constructing the floor. (Is it generally possible to install infrared heating under the screed here?)
Additionally, I want to create a simple counter slope to prevent water from being drawn toward the partition wall.
My options so far:
1.
- Seal the floor slab with a bitumen membrane,
- Lay 10 mm (0.4 inches) Styrodur or polystyrene boards smoothly,
- Attach edge insulation strips,
- Mount underfloor heating on top,
- Apply a floating cement screed with a slope of 4–6 cm (1.6–2.4 inches) on top,
- Done
2.
- Seal the floor slab with a bitumen membrane,
- Lay 10 mm (0.4 inches) Styrodur or polystyrene boards and stack them toward the back to create a level base for the screed of uniform thickness,
- Attach edge insulation strips,
- Mount underfloor heating on top,
- Apply a floating cement screed with a slope of 4–6 cm (1.6–2.4 inches) on top,
- Done
Or is a floating screed not advisable for a garage? What about screed thicknesses—are they sufficient for the load under cars? Can I have the cement screed installed at the same time as the house screed, or does it need to be a special type of screed?
The 10 mm (0.4 inches) boards are mainly to prevent the heating cables from damaging the bitumen membrane and slightly for retaining heat from the heating system.
I would appreciate any helpful answers and tips.
I am currently researching garage floors and wanted to ask my question here.
The garage is attached to the house, and the floor slab was poured together with the one for the house. It is a foundation slab made of waterproof concrete, reinforced with steel mesh (WU) C 25/30, serving as a load-bearing element with an encircling frost skirt made of steel fiber concrete C 25/30 (0.80 x 0.30 m (2 ft 7 in x 1 ft)), without additional insulation.
There is about 6.30 m (21 ft) of space in front for cars and about 2.15 m (7 ft) at the back for a workshop/storage area.
The garage is not intended for permanent occupancy, but I want to be able to work on my car or motorcycle in winter without freezing my feet or kidneys while lying on the floor. Therefore, I would like to include electric underfloor heating when constructing the floor. (Is it generally possible to install infrared heating under the screed here?)
Additionally, I want to create a simple counter slope to prevent water from being drawn toward the partition wall.
My options so far:
1.
- Seal the floor slab with a bitumen membrane,
- Lay 10 mm (0.4 inches) Styrodur or polystyrene boards smoothly,
- Attach edge insulation strips,
- Mount underfloor heating on top,
- Apply a floating cement screed with a slope of 4–6 cm (1.6–2.4 inches) on top,
- Done
2.
- Seal the floor slab with a bitumen membrane,
- Lay 10 mm (0.4 inches) Styrodur or polystyrene boards and stack them toward the back to create a level base for the screed of uniform thickness,
- Attach edge insulation strips,
- Mount underfloor heating on top,
- Apply a floating cement screed with a slope of 4–6 cm (1.6–2.4 inches) on top,
- Done
Or is a floating screed not advisable for a garage? What about screed thicknesses—are they sufficient for the load under cars? Can I have the cement screed installed at the same time as the house screed, or does it need to be a special type of screed?
The 10 mm (0.4 inches) boards are mainly to prevent the heating cables from damaging the bitumen membrane and slightly for retaining heat from the heating system.
I would appreciate any helpful answers and tips.
Hello questioner.
Actually, I should start my answer with your last question, as it covers all the other points.
Quote: "Or does a floating screed have no place in the garage?"
Answer: Yes, a floating screed actually does not belong in a garage. Due to the stresses from driving (dynamic loads) and point loads, bonded construction systems are installed on such surfaces. No "floating" screeds or screeds on a separating layer!
--------
Regarding your options:
Waterproofing against rising moisture from the rear is also not advisable. In the open build-up you are planning, water vapor—which also passes through waterproof concrete—will unnoticed transfer to the indoor air.
-----------------
Counter-slope:
A counter-slope must definitely be avoided, as it always directs water towards components that need protection.
What you mean is a slope!
This is generally designed so that it neither drains into the room nor towards the walls.
-------------
Underfloor heating:
I advise against it due to the enormous effort involved.
Heating is usually integrated in the concrete (so-called thermal core activation), which also requires thermal insulation beneath the slab.
Installing underfloor heating on such a slab, even with a bonded screed, will inevitably result in significant heat loss (because there is no insulation).
A more practical and simpler option is infrared heating installed in the ceiling.
At the eventual workstation, a thicker rubber granulate mat is laid down, which adequately reduces heat loss underfoot for the time being.
------------------------
(Quote) "... so that water cannot be drawn towards the partition wall"
Answer: Picking up these lines written in a different context, my remark is that the final screed surface will have to be treated with a surface protection, so the screed surface will undergo appropriate preprocessing.
In this context, a slope can also be installed. Ideally (since the slope practically has to go to "ZERO"), an epoxy mortar is preferred here before rolling on a surface seal over the entire area.
-----------------
(Quote) "What about the thicknesses? Is that enough to support the load under a car?"
Answer:
For a bonded screed, as I recommended, about 25 mm (1 inch) thickness is sufficient.
For a car, a screed on insulation should be approximately 65 to 70 mm (2.5 to 2.75 inches), plus the thickness of the insulation layer.
If you want to install a water-based underfloor heating system, about 15 mm (0.6 inches) would be added to the screed thickness mentioned.
My assessment: You simply cannot achieve the necessary build-up height in a normal garage!
----------------------------------
Final remark:
Even in this case, without professional expertise, you cannot create a proper trade installation. Even if advertising may promise otherwise.
From professional experience (as an expert), I simply say: the seemingly cost-effective attempt to do something yourself can ultimately be the most expensive way.
Nevertheless, good luck with your project:
KlaRa
Actually, I should start my answer with your last question, as it covers all the other points.
Quote: "Or does a floating screed have no place in the garage?"
Answer: Yes, a floating screed actually does not belong in a garage. Due to the stresses from driving (dynamic loads) and point loads, bonded construction systems are installed on such surfaces. No "floating" screeds or screeds on a separating layer!
--------
Regarding your options:
Waterproofing against rising moisture from the rear is also not advisable. In the open build-up you are planning, water vapor—which also passes through waterproof concrete—will unnoticed transfer to the indoor air.
-----------------
Counter-slope:
A counter-slope must definitely be avoided, as it always directs water towards components that need protection.
What you mean is a slope!
This is generally designed so that it neither drains into the room nor towards the walls.
-------------
Underfloor heating:
I advise against it due to the enormous effort involved.
Heating is usually integrated in the concrete (so-called thermal core activation), which also requires thermal insulation beneath the slab.
Installing underfloor heating on such a slab, even with a bonded screed, will inevitably result in significant heat loss (because there is no insulation).
A more practical and simpler option is infrared heating installed in the ceiling.
At the eventual workstation, a thicker rubber granulate mat is laid down, which adequately reduces heat loss underfoot for the time being.
------------------------
(Quote) "... so that water cannot be drawn towards the partition wall"
Answer: Picking up these lines written in a different context, my remark is that the final screed surface will have to be treated with a surface protection, so the screed surface will undergo appropriate preprocessing.
In this context, a slope can also be installed. Ideally (since the slope practically has to go to "ZERO"), an epoxy mortar is preferred here before rolling on a surface seal over the entire area.
-----------------
(Quote) "What about the thicknesses? Is that enough to support the load under a car?"
Answer:
For a bonded screed, as I recommended, about 25 mm (1 inch) thickness is sufficient.
For a car, a screed on insulation should be approximately 65 to 70 mm (2.5 to 2.75 inches), plus the thickness of the insulation layer.
If you want to install a water-based underfloor heating system, about 15 mm (0.6 inches) would be added to the screed thickness mentioned.
My assessment: You simply cannot achieve the necessary build-up height in a normal garage!
----------------------------------
Final remark:
Even in this case, without professional expertise, you cannot create a proper trade installation. Even if advertising may promise otherwise.
From professional experience (as an expert), I simply say: the seemingly cost-effective attempt to do something yourself can ultimately be the most expensive way.
Nevertheless, good luck with your project:
KlaRa
Hello KlaRa,
thank you for your reply.
First of all: I only take on tasks myself when I am really sure I can do them correctly. And I usually have the work checked afterwards by the appropriate specialists.
You are completely right. Many DIY efforts fail and then end up costing more.
But I don’t necessarily want to install the screed myself. It will probably be laid together with the house screed. I just wanted to explore the best option for my needs first.
I realize now that I should forget about the fixed idea of underfloor heating. Ceiling heating would probably make more sense.
I think I misunderstood or misused the term “counter slope.” I only meant to say that there isn’t a sufficient slope to allow water to flow, but at least it prevents water from moving towards the inside wall.
So your recommendation is a 25mm (1 inch) bonded screed without a waterproofing layer, smoothed with epoxy mortar and sealed?
Am I summarizing that correctly?
What advantage does the screed offer compared to smoothing directly with epoxy mortar?
thank you for your reply.
First of all: I only take on tasks myself when I am really sure I can do them correctly. And I usually have the work checked afterwards by the appropriate specialists.
You are completely right. Many DIY efforts fail and then end up costing more.
But I don’t necessarily want to install the screed myself. It will probably be laid together with the house screed. I just wanted to explore the best option for my needs first.
I realize now that I should forget about the fixed idea of underfloor heating. Ceiling heating would probably make more sense.
I think I misunderstood or misused the term “counter slope.” I only meant to say that there isn’t a sufficient slope to allow water to flow, but at least it prevents water from moving towards the inside wall.
So your recommendation is a 25mm (1 inch) bonded screed without a waterproofing layer, smoothed with epoxy mortar and sealed?
Am I summarizing that correctly?
What advantage does the screed offer compared to smoothing directly with epoxy mortar?
Hello questioner.
The answer to your question is simply: a significant cost saving.
By installing a composite screed (as I understand, the screed is still to be installed in the house), you can definitely create the slope immediately during the installation. This seems to me the best option.
The question is whether there is enough build-up height available to drain the rear part of the garage.
For optimal drainage, you need 2cm (about 0.8 inches) per meter in the (garage) depth, plus 1cm (about 0.4 inches) overall thickness.
This means for a length of 6m (about 20 feet) a screed thickness of 12cm (about 4.7 inches) + 1cm (about 0.4 inches) = 13cm (about 5.1 inches) in the rear section, and 1cm (about 0.4 inches) in the front section.
Since the screed must be protected from later damaging influences (!), after a thorough grinding, priming, and scratch coating with a filled reactive resin, the screed surface will be prepared in terms of porosity and flatness, allowing for the application of a standard concrete paint (available at any hardware store) by roller.
However, nothing is permanently abrasion resistant as claimed in advertising.
The expected service life of the sealant (concrete paint) will be in the range of 3 to 5 years, depending on the level of stress.
Best regards, KlaRa
The answer to your question is simply: a significant cost saving.
By installing a composite screed (as I understand, the screed is still to be installed in the house), you can definitely create the slope immediately during the installation. This seems to me the best option.
The question is whether there is enough build-up height available to drain the rear part of the garage.
For optimal drainage, you need 2cm (about 0.8 inches) per meter in the (garage) depth, plus 1cm (about 0.4 inches) overall thickness.
This means for a length of 6m (about 20 feet) a screed thickness of 12cm (about 4.7 inches) + 1cm (about 0.4 inches) = 13cm (about 5.1 inches) in the rear section, and 1cm (about 0.4 inches) in the front section.
Since the screed must be protected from later damaging influences (!), after a thorough grinding, priming, and scratch coating with a filled reactive resin, the screed surface will be prepared in terms of porosity and flatness, allowing for the application of a standard concrete paint (available at any hardware store) by roller.
However, nothing is permanently abrasion resistant as claimed in advertising.
The expected service life of the sealant (concrete paint) will be in the range of 3 to 5 years, depending on the level of stress.
Best regards, KlaRa
Similar topics