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Blockwork
Rising walls, cavity walls, boundary and garden walls and retaining walls, built plumb and level on a foundation that was set out properly in the first place.
in short
AltHome builds blockwork across Kerry, Cork and Limerick: rising walls, cavity walls, boundary and garden walls and retaining walls, in the standard 215 mm Irish block. Walls go up on a foundation set out and dug to firm ground, with an unbroken damp proof course, and foundations and retaining walls are signed off by an engineer. Jobs run from three days to three weeks.
what decides it
What is holding it up, and what is keeping it dry
A block wall is only as good as what is under it and what is tying it together. Under a house wall that means a foundation dug to firm ground, wide enough for the load, with steel where the engineer calls for it, and rising walls built off it in dense blocks up to a damp proof course that runs unbroken and laps into the radon barrier and the floor membrane. Break the DPC at one doorway and you have a permanent damp patch that no amount of paint will cure. Above the DPC the external wall is usually a cavity: two leaves of block with insulation in between, stainless ties at the right spacing and staggered, kept clean of mortar droppings so nothing bridges the gap, cavity closers at every opening, and trays and weeps over lintels and doorways so water that gets into the cavity is sent back out instead of down onto the inner leaf. That detailing is boring and invisible and it is the entire difference between a warm dry wall and a wall that stains on the inside every winter. Garden and boundary walls fail for a different reason: they are built too thin, too tall, with no piers and no capping. Wind load on a free standing wall is real, and water sitting in an open block top freezes and splits it. So anything over about a metre and a bit gets piers or thickening, steel down into the foundation where the height needs it, movement joints on a long run, and a solid capping so the top is closed. A retaining wall is a structure, not a tall garden wall: it needs drainage stone and a pipe behind it, weep holes through it, and reinforcement sized by an engineer, because the ground behind it is pushing all day and after rain it pushes harder.
Mortar, weather and the first week
Mortar is mixed to a gauge, not by eye, and the mix changes with the job: stronger below ground, softer against old stone so the wall moves without cracking the stone faces. New work is covered at the end of every day, because a night of rain washes a fresh joint out and a hard frost in the first days ruins the set. We do not lay in frost and we do not lay onto frozen blocks. Waiting two days is cheaper than taking a wall down in March.
the work
What is included in blockwork?
- Set out the lines and levels off the drawings and check them against what is actually on the ground.
- Dig and pour the foundation, with steel and an engineer inspection where it is needed.
- Build the rising walls, lay the DPC unbroken and tie it into the radon barrier and floor membrane.
- Lay the cavity leaves with clean ties, insulation, closers, lintels, trays and weeps at every opening.
- Build piers, movement joints and capping on free standing walls, and drainage behind retaining walls.
- Point up, clean off, cover the new work overnight and leave the site tidy for the next trade.
4 steps
How long does it take to build a block wall?
You get in touch
Tell us what the wall is for and send the drawings if you have them. We answer the same day.
We come and look
Ground conditions, levels, access for a mixer and a dumper, and whether the job needs an engineer. Then a written price per stage.
We build it
Foundation, rising walls, cavity, openings. You get photos of the foundation and the DPC before they disappear under the next layer.
You sign it off
We walk the wall with you, hand over the engineer certificates where they apply, and clear the site.
next door
What goes around it
Blockwork rarely arrives on its own. It sits between the groundwork and everything that gets fixed to the wall afterwards.
asked
Blockwork: common questions
How high can a garden wall go without permission?
A wall to the front of a house is limited to about 1.2 metres under the exemption, and roughly 2 metres to the side or rear, with the capping counted in. Corner sites and sight lines at an entrance have their own rules. We check it before we price it rather than after you have paid for blocks.
Do I need an engineer?
For a low garden wall, no. For foundations under a house or extension, for anything retaining ground, and for any wall that will carry a steel or a roof, yes, and you want that certificate on file for the day you sell the house. We work to the engineer’s detail and call them for inspection at the right stages.
Can you build onto an existing wall?
Often, but it depends what the existing wall is standing on. We expose the foundation at one point and look before committing. Tying new blockwork to an old wall that is already moving just transfers the crack into your new work.
How much does a block wall cost to build?
The cost is set by the length and height, how deep the foundation has to go, whether it is plastered or rendered, and whether it retains ground. A retaining wall costs far more than a garden wall of the same size because of the steel, drainage and engineering. We measure and give a written price.
Does a garden wall need to be rendered?
A block wall should be rendered or clad on any face exposed to the weather, because bare block soaks up rain and breaks down at the joints. A capping on top keeps water out of the core. Both are included in our price unless you ask otherwise.
quote
Get a fixed quote for blockwork
Tell us the address and the length and height you have in mind. We work across Kerry, Cork and Limerick. We ring you back within one working day. Drawings or photos of the site make the price tighter.
085 220 1422 · info@althome.ie
Written by the AltHome crew. Last reviewed September 2026.