Porch steps refurbishment.

[BarumMike]

Help required to plan the refurbishing of the steps up to the pillared porch of our Regency house. I attach photos. As you can see there are 4 slate steps with the risers tiled with Victorian encaustic decorative tiles. The bottom three risers have blown outward dislodging/breaking many of the tiles.

1. I assume this is likely to be due to damp penetration into the cement mortar behind the tiling?
2. Apart from windblown rain, the porch roof has been leaky adding to the volume of water lying on the steps. There is no fall of the slate to shed water from the steps. Is water penetration through the bottom of the risers a plausible explanation of the damage?
3. We also have a problem with water not draining away into the ground below the gravel around the steps. Is it essential we address this? Not simple for a variety of reasons.
4. Is it enough to excavate horizontally for an inch or two into the mortar bed below each step before recreating a new vertical mortar face for the replacement tiles?
5. Is there a way of sealing/waterproofing the newly tiled riser to prevent future water damage?

I may not be asking the right questions. Any comments gratefully received!

 

[Cubist]

Hello and welcome,
I've embedded answers to your specific questions in the text below. Hope this helps and I'm sure other members will be along soon to offer more advice.
Cheers,
Cubist

Help required to plan the refurbishing of the steps up to the pillared porch of our Regency house. I attach photos. As you can see there are 4 slate steps with the risers tiled with Victorian encaustic decorative tiles. The bottom three risers have blown outward dislodging/breaking many of the tiles.

1. I assume this is likely to be due to damp penetration into the cement mortar behind the tiling? Yes, rain-water will have bled through the mortar used to grout the tiles in place and that used to fix them to the stone/block-work below.
2. Apart from windblown rain, the porch roof has been leaky adding to the volume of water lying on the steps. There is no fall of the slate to shed water from the steps. Is water penetration through the bottom of the risers a plausible explanation of the damage? Pooling water will sit against the grout lines and be absorbed beneath the lower edge of the tiles at the back and through the render at the sides.
3. We also have a problem with water not draining away into the ground below the gravel around the steps. Is it essential we address this? Not simple for a variety of reasons. Can you be more specific or provide a photo please?
4. Is it enough to excavate horizontally for an inch or two into the mortar bed below each step before recreating a new vertical mortar face for the replacement tiles? No. Frankly, unless there is considerable damage to to the stone/block-work behind the tiles then theres no advantage. In fact that this may introduce risk of greater damage.
5. Is there a way of sealing/waterproofing the newly tiled riser to prevent future water damage? There are but I would advise against their use externally as sealing the surface of the tiles would create an impermeable barrier behind which water , accumulating from other routes, can be trapped.

 

[BarumMike]

Cubist, thanks for the very helpful replies. Answers to questions 1 noted.
Qu 2. Your answer noted. To rebed the slate steps to correct the fall and direct rain away from the lower joint line of slate and riser tiles would be a major undertaking. I wonder if I can get a pair of drainage grooves cut or ground into the top surface of each slate?
Qu 3. Ground water drainage. I attach a photo to show the steps and the space between the parapet wall of the steps and the adjacent bay window. Rainwater pools and is slow to drain away from to the right of front of the parapet wall and over the slate flagstone at the foot of the steps. So I suspect that damp is also getting into the stone/blockwork under the steps from the subsoil. The riser of the lowest step is the most damaged, with the centre tiles pushed 3.5cm outwards compared with the tiles at each corner of the riser (detail photo attached). Perhaps the answer to my question is obvious ie I do need to improve the clearance of rainwater from the ground around the steps.
Qu 4. Noted altho the lowest riser face is pushed out by 3.5cm in the centre, and more work may be needed there. I assume cement mortar can be used for the repairs and for bedding of the new tiles?
Qu 5. Noted. Could you just seal the joint line between slate and the lower run of riser tiles of each tile face?

 

[Cubist]

Hello again,

Qu 2. Your answer noted. To rebed the slate steps to correct the fall and direct rain away from the lower joint line of slate and riser tiles would be a major undertaking. I wonder if I can get a pair of drainage grooves cut or ground into the top surface of each slate?

Could be done with a small angle grinder but the wear pattern to the surface of the slate may work against discrete positioning. Also, you would really need to be very comfortable with using an angle grinder as you can very easily damage the slates appearance. Try pouring some water over each step and note the waters course, if any to the front edge.

Qu 3. Ground water drainage. I attach a photo to show the steps and the space between the parapet wall of the steps and the adjacent bay window. Rainwater pools and is slow to drain away from to the right of front of the parapet wall and over the slate flagstone at the foot of the steps. So I suspect that damp is also getting into the stone/blockwork under the steps from the subsoil. The riser of the lowest step is the most damaged, with the centre tiles pushed 3.5cm outwards compared with the tiles at each corner of the riser (detail photo attached). Perhaps the answer to my question is obvious ie I do need to improve the clearance of rainwater from the ground around the steps.

Have you considered a small gulley to carry surface water away from where its pooling?

Qu 4. Noted altho the lowest riser face is pushed out by 3.5cm in the centre, and more work may be needed there. I assume cement mortar can be used for the repairs and for bedding of the new tiles?

Sadly the tiles need to come off and all the loose material behind removed before a new bed can be made for the tiles. Some of the mortar in your photos looks like a Portland cement may have been used. If the old bedding layer for the tiles was a lime mortar the newer cement will not bond well with it and cracks and other degradation is inevitable. May be an idea to get rid of any all cement mortar and replace with lime.

Qu 5. Noted. Could you just seal the joint line between slate and the lower run of riser tiles of each tile face?

That's feasible but not likely to have any major benefits. Best to stick to just one grouting compound, lime mortar) as then you can rely on the bonds at any intersections.