Hello,
I want to install natural stone window sills myself inside our house.
At the building materials store, they recommended hydraulic lime mortar for the installation.
... So far, so good ...
What should I pay attention to during the installation?
Is the mortar applied with a notched trowel (like for tiles)?
Or, based on my intuition, should I lay the stone slabs into a "mortar bed" and then level them with a spirit level?
Do I need to treat the slabs or the substrate beforehand, such as with a primer?
The window sills will be attached to sand-lime bricks and the plaster on top of them.
I want to install natural stone window sills myself inside our house.
At the building materials store, they recommended hydraulic lime mortar for the installation.
... So far, so good ...
What should I pay attention to during the installation?
Is the mortar applied with a notched trowel (like for tiles)?
Or, based on my intuition, should I lay the stone slabs into a "mortar bed" and then level them with a spirit level?
Do I need to treat the slabs or the substrate beforehand, such as with a primer?
The window sills will be attached to sand-lime bricks and the plaster on top of them.
A
AallRounder9 Jan 2010 12:45Back then, I also installed granite in hydraulic mortar containing trass...
A horizontal formwork board with plaster anchors was fixed on the front side to mark the future height of the window sill, taking into account any desired slope. Since condensation can occur on the windows and water can accumulate on the sill, a slight slope might be useful. In most cases, the amount of water is probably low enough that an internal slope can be omitted, in my opinion. This allows “her” to place flowerpots on the sill later without them tilting.
The sand-lime bricks absorb moisture very strongly and, in my opinion, need to be well pre-wetted (but no puddles!). As long as the bricks still appeared dark from moisture, I applied the hydraulic mortar evenly with a trowel, and then smoothed it along the formwork board (an aluminum straightedge with an integrated spirit level), carefully maintaining the level or any desired slope relative to the window. Into the carefully leveled mortar bed, I laid the well pre-wetted window sill. I moved it slightly back and forth to ensure full-surface contact. Nothing is worse than a natural stone window sill resting on hollow spaces. A simple pressure or a large flowerpot from the wife and: crack!
In my opinion, the sill should definitely not touch the window frame, so I left a 3-5mm (0.1-0.2 inch) gap. This joint was later sealed with silicone suitable for natural stone. Granite expands, and plastic even more so, so a tightly fitted installation could cause problems, in my view.
The interior window sills can each be recessed about 2cm (0.8 inches) into the reveals. This can be achieved by an appropriate plaster overlap on the reveal without the need for chiseling. Here, too, I would recommend including expansion joints, for example by inserting strips of styrofoam.
I’m not a professional; this is how I did it and have had no problems so far (installation was 8 years ago).
Regards
A horizontal formwork board with plaster anchors was fixed on the front side to mark the future height of the window sill, taking into account any desired slope. Since condensation can occur on the windows and water can accumulate on the sill, a slight slope might be useful. In most cases, the amount of water is probably low enough that an internal slope can be omitted, in my opinion. This allows “her” to place flowerpots on the sill later without them tilting.
The sand-lime bricks absorb moisture very strongly and, in my opinion, need to be well pre-wetted (but no puddles!). As long as the bricks still appeared dark from moisture, I applied the hydraulic mortar evenly with a trowel, and then smoothed it along the formwork board (an aluminum straightedge with an integrated spirit level), carefully maintaining the level or any desired slope relative to the window. Into the carefully leveled mortar bed, I laid the well pre-wetted window sill. I moved it slightly back and forth to ensure full-surface contact. Nothing is worse than a natural stone window sill resting on hollow spaces. A simple pressure or a large flowerpot from the wife and: crack!
In my opinion, the sill should definitely not touch the window frame, so I left a 3-5mm (0.1-0.2 inch) gap. This joint was later sealed with silicone suitable for natural stone. Granite expands, and plastic even more so, so a tightly fitted installation could cause problems, in my view.
The interior window sills can each be recessed about 2cm (0.8 inches) into the reveals. This can be achieved by an appropriate plaster overlap on the reveal without the need for chiseling. Here, too, I would recommend including expansion joints, for example by inserting strips of styrofoam.
I’m not a professional; this is how I did it and have had no problems so far (installation was 8 years ago).
Regards
Hi,
Trass cement is a good choice.
Personally, I skip the formwork board, spread the mixture over the surface, slide the windowsill under the window frame, and make sure it doesn’t hit the back edge. Then, using a small spirit level, I level it horizontally.
To avoid a direct connection of materials (thermal bridge), I press two small wedges under the back of the frame. This creates a slight backward slope, which is a topic of debate.
If you create a forward slope or install the windowsill perfectly level, you often get the optical illusion that the sill is about to slide out.
I prefer a slight backward slope and occasionally wipe away any condensation with a cloth rather than having water run into the room.
Regards, Dirk
Trass cement is a good choice.
Personally, I skip the formwork board, spread the mixture over the surface, slide the windowsill under the window frame, and make sure it doesn’t hit the back edge. Then, using a small spirit level, I level it horizontally.
To avoid a direct connection of materials (thermal bridge), I press two small wedges under the back of the frame. This creates a slight backward slope, which is a topic of debate.
If you create a forward slope or install the windowsill perfectly level, you often get the optical illusion that the sill is about to slide out.
I prefer a slight backward slope and occasionally wipe away any condensation with a cloth rather than having water run into the room.
Regards, Dirk
A
AallRounder15 Jan 2010 17:54Yeah, cool,
accomplished something again. Interesting site; I’ll have to take a closer look at it sometime.
Wishing you continued success!
Regards
accomplished something again. Interesting site; I’ll have to take a closer look at it sometime.
Wishing you continued success!
Regards
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