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.
As described in the initial post, there will be no slope for proper drainage.
There is simply too little water here, and to be honest, I do not want to go up to a 13 cm (5 inch) build-up.
Given how I understand the situation, I would proceed as follows:
Have the screed applied directly onto the untreated and unsealed concrete slab. (Do bonded screeds usually include edge insulation strips?) At the front, 25 mm (1 inch), at the back 50 mm (2 inches) tapering down over 6 meters (20 feet). The remaining 3 meters (10 feet) at the rear stay flat at 50 mm (2 inches). (Shelf storage area and workshop section)
After the appropriate waiting time, grind, prime, and treat with resin. Finally, apply concrete paint and you’re done.
Buy a rubberized mat and infrared heating and enjoy working even in winter.
There is simply too little water here, and to be honest, I do not want to go up to a 13 cm (5 inch) build-up.
Given how I understand the situation, I would proceed as follows:
Have the screed applied directly onto the untreated and unsealed concrete slab. (Do bonded screeds usually include edge insulation strips?) At the front, 25 mm (1 inch), at the back 50 mm (2 inches) tapering down over 6 meters (20 feet). The remaining 3 meters (10 feet) at the rear stay flat at 50 mm (2 inches). (Shelf storage area and workshop section)
After the appropriate waiting time, grind, prime, and treat with resin. Finally, apply concrete paint and you’re done.
Buy a rubberized mat and infrared heating and enjoy working even in winter.
After consulting with the screed installer, I received the following information:
A bonded screed is unlikely because the concrete slab would need to be shot-blasted first. For this relatively small area, it is simply not cost-effective to find someone to do that.
This means a screed with a separating layer would have to be applied. However, in the driveway area, it would need a minimum thickness of 50mm (2 inches), increasing to 80mm (3 inches) towards the rear area due to the low slope.
Is this understandable? It’s not actually the answer I was hoping for. ops:
A bonded screed is unlikely because the concrete slab would need to be shot-blasted first. For this relatively small area, it is simply not cost-effective to find someone to do that.
This means a screed with a separating layer would have to be applied. However, in the driveway area, it would need a minimum thickness of 50mm (2 inches), increasing to 80mm (3 inches) towards the rear area due to the low slope.
Is this understandable? It’s not actually the answer I was hoping for. ops:
Hello "Patkia".
Just before logging off for my vacation, a quick note regarding the feedback from the screed installer:
The shot blasting method indeed requires a corresponding surface area.
As a screed installer, he should be familiar with the alternative option, which is also common in practice, that the base slab to be prepared can either be ground or brushed using a steel brush attachment with a single-disc machine.
Please don’t let him convince you that there is only one possible procedure.
I admit that he will likely earn more with a thicker screed than with a 25mm (1 inch) thick bonded screed, but that should not be the deciding factor here.
His claim regarding 50mm (2 inches) is clearly incorrect since the screed (now to be installed as a separation-layer screed) cannot handle the expected traffic load. It is undersized at 50mm (2 inches).
The minimum thickness for a flexural tensile strength class of F4, with a surface load of 5kN/m² (which corresponds to a heavier sedan), should be at least 70mm (3 inches), and for F5 at least 60mm (2.5 inches). And that at the lowest point!
If the screed is also to be designed as a sloped screed, this no longer fits at all.
With an additional 30mm (1 inch) to 40mm (1.5 inches), optimal compaction of the lower screed structure will no longer be possible on the one hand, and the screed (except for bonded screed) must be applied as evenly thick as possible.
Otherwise, it will crack all over the place, which will be quite a problem. And unfortunately, this is no joke!
Please specify a bonded screed to him after proper mechanical preparation and tell him that the project and his work are being monitored by a certified screed expert from the building surveyor’s association behind the scenes...
Good luck, signing off now!
Best regards, KlaRa
Just before logging off for my vacation, a quick note regarding the feedback from the screed installer:
The shot blasting method indeed requires a corresponding surface area.
As a screed installer, he should be familiar with the alternative option, which is also common in practice, that the base slab to be prepared can either be ground or brushed using a steel brush attachment with a single-disc machine.
Please don’t let him convince you that there is only one possible procedure.
I admit that he will likely earn more with a thicker screed than with a 25mm (1 inch) thick bonded screed, but that should not be the deciding factor here.
His claim regarding 50mm (2 inches) is clearly incorrect since the screed (now to be installed as a separation-layer screed) cannot handle the expected traffic load. It is undersized at 50mm (2 inches).
The minimum thickness for a flexural tensile strength class of F4, with a surface load of 5kN/m² (which corresponds to a heavier sedan), should be at least 70mm (3 inches), and for F5 at least 60mm (2.5 inches). And that at the lowest point!
If the screed is also to be designed as a sloped screed, this no longer fits at all.
With an additional 30mm (1 inch) to 40mm (1.5 inches), optimal compaction of the lower screed structure will no longer be possible on the one hand, and the screed (except for bonded screed) must be applied as evenly thick as possible.
Otherwise, it will crack all over the place, which will be quite a problem. And unfortunately, this is no joke!
Please specify a bonded screed to him after proper mechanical preparation and tell him that the project and his work are being monitored by a certified screed expert from the building surveyor’s association behind the scenes...
Good luck, signing off now!
Best regards, KlaRa
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