The K-Zone: A porch too far: Bricklaying

I must point out from the outset that I'm not much of a bricklayer. I can do it, if I have to; but I'm very slow, and also rather untidy. So I confess that I had a lot of help with this part of the job. It still took two of us nearly four days to do the work -- unless you build houses for a living, good bricklaying is a slow, painstaking job, and can't really be rushed.
Although I can describe in outline how and why we did things, the craft skill of bricklaying is not really something that can be described in writing, in my view. It needs to be demonstrated, and then practised. Quite a lot.

A brick is a brick

When I started this job, I was mildly surprised at how large the potential choice of house bricks is. A fundamental distinction is between bricks that are intended to be on display, and bricks that are not. Prices for latter start from about 20p each; display bricks can be priced in the pounds each. Reclaimed bricks, surprisingly, are quite expensive despite being second-hand. I imagine that's because it costs money to have all the mortar and grot cleaned off them. The cheapest bricks I have been able to find of any type were Wickes-brand engineering bricks, which come in at 19p each if ordered in a pallet of 500. These bricks are easy to lay, but they are strikingly ugly. In addition, I've found that engineering bricks are very brittle, and don't take well to drilling -- they tend to shatter. In any case, I wasn't intending to built a multi-storey car park.
What this distinction between display and non-display bricks means is that, from the outset, a decision has to be made whether you expect your brickwork to remain visible, or to be rendered over. For my part, I wanted brickwork that would not be offensive if it were not rendered, but I intended (and still intend) to render it at some point. In the end I settled on a compromise and ordered LBC regrade bricks. Regrade bricks are generally displayable, but have come out of the brickworks slightly imperfect -- perhaps too much colour variation in a pallet. You can see the colour variation in my delivery of bricks in the photos in this article -- colours range from classic red to almost orange. In my view, this colour variation is not offensive, but is quite noticeable next to the brick walls of the house itself, which are perfectly uniform.
LBC regrades are not the cheapest bricks on the market -- for this job they worked out at about 25p each -- but they represent a reasonable compromise between cost and appearance.

It's not difficult to work out how many bricks you'll need for the job, if you bear in mind that the mortared size of a standard UK brick is about 9 inches long by 3 inches high. That's allowing for the recommended half-inch of mortar between bricks. But unless you're highly practised, or very lucky, there will be a certain amount of wastage in cutting. For the record, my porch required required 530 bricks, of which about 30 ended up as rubble.

Starting off

Find a layout arrangement of bricks that will minimise cutting, but bear in mind that you need at least a small overlap at the corners for support

It isn't all that difficult to cut house bricks: just put a bolster chisel on the line you want to cut, and smack it hard with a club hammber. If you're lucky, the brick will cleave cleanly along the cut line. If you're somewhat unlucky it will cleave in the wrong place, but leave you two pieces you can use elsewhere. If you're very unlucky, you'll end up with a pile of shards.
In any event, if you have flexibility in the size of your building, it's best to arrange things to minimise the amount of cutting. Generally, a smaller building will always require a greater proportion of cut bricks, and the cutting will add significantly to the time it takes. That's not because the cutting itself is time-consuming, but if you're working up a ladder or a scaffold, you'll have to climb down, cut the brick, and climb back up again. It's all good exercise, of course.
It's very important at the outset to mark out straight edges for a reference for the brickwork. For a porch that usually means projecting a string at right-angles from the front of the house to form the first reference line, then measuring the others from that. You can lay bricks with half-inch spacings along the reference strings to get the proper sizes. You can finally check that your proposed porch outline is perfectly rectangular, and not trapezoidal, by measuring corner-to-corner in each direction. These measurements should be identical.

There's mortar this than meets the eye

For making bricklaying mortar, you need soft sand. Sand sold for general building applications is usually sharp, and not ideal for bricklaying. In my experience, for example, Wickes building sand, which claims to be suitable for bricklaying, really isn't. It's very hard to get it to a consistency where it will stick nicely to the bricks. A good mortar mix needs to have a texture rather like soft cheese -- it should be smooth, not runny, and be able to stick upside down. Of course, you won't be laying bricks under a ceiling, but the mortar should be of such a consistency that it would stick to a ceiling if you put it there.
Most builders make mortar with 3-5 parts of soft sand to one part of standard Portland cement. This cement is slow drying. Using quick-drying cement for bricklaying is only for experts and masochists. A standard mortar mix will remain workable for several hours at least in the London autumn climate. A splash of mortar plasticiser help to keep the mix smooth, but Fairy Liquid will do at a pinch.
I can't recommend a cement mixer higly enough for a job even of this modest scale. For this job I used four bags of cement and 20 of sand. That's a lot of mixing to do with a spade.

Slow and steady does it

My experience is that inaccuracies introduced in the first couple of courses of brickwork can only get worse as the job progresses. Of particular concern are the corners furthest from the house because, at this stage of the job, you don't have any vertical reference line. So far as I can tell, there is no clever or subtle way of keeping these corners vertical -- you just have to keep checking everything, over and over again, with a level. There's no shame in taking out a whole bunch of bricks and starting again if, for example, it turns out that you squeezed out too much mortar to be able to bring all the bricks in the course to the same height.

The quality of the finished brickwork depends on frequent and meticulous checking with a level, in all three directions

Ideally you should point the brickwork after the bricks have been laid long enough for the mortar to start to set. Pointing is the process of squeezing the mortar into the gaps between the bricks with a round-ended trowel. This tidies up the finish enormously. I've sometimes been told that pointing is necessary to improve the strength of the mortar bond. I'm not entirely sure I believe that, but it's possible.
I was finding that I had to wait about six hours, with our mortar mix and in the October weather, for the brickwork to be ready to point. So I generally ended up doing the pointing in the dark with a torch, and that's why some of it isn't very good, to be honest. The upper courses are particularly rough, because we finished the bricklaying itself at about 4pm, and by 10pm it still wasn't really ready to point. So I went to bed. When I woke up and got back on with the job, the mortar had already set. Oh, well.

The damp-proof barrier stops water rising into the body of the porch, and needs to be at or close to the same level as in the main building

It's important when building a porch not to bridge the damp-proof course in the main building. Ideally, you want the damp-proof course in the porch to be at exactly the same level as that in the main building, but such precision is quite difficult to achieve. But if you can find the original damp proof course (and, in my case, that meant hacking some of the render off the house) you should be able to get quite close.
Damp-proof membrane is inexpensive -- at least in the quantities you need for a porch -- so there's little benefit in using the cheap, nasty stuff. Decent damp proof membrane is thick and heavy, holds its shape when rolled out, and bonds nicely to mortar. You need a layer of mortar above and below the membrane itself -- the membrane will certainly not bond directly to brick.

Getting along

In practice, all brick buildings settle on their foundations as the mortar dries. It may even be the case that the foundation sinks slightly under the added weight of the building. That's to be expected, but you don't want a huge gap to open up between the porch and the house when this happens. So common practice is to bolt metal `starter ties' to the house wall and anchor the porch brickwork to these (see photo). Starter ties are surprisingly expensive because they're made of stainless steel to be rust-proof. The ties have a runner into which right-angle pieces are slid. Typically one right-angle piece is inserted into each third course of bricks. The ties allow a bit of vertical movement, but very little horizontal movement, so even if the porch settles it won't pull away from the house.

Stainless steel starter ties create a bond between the buildings, and provide a vertical reference line

It's conventional to insert airbricks into the brickwork below floor level, if there is a gap between the floor and the foundation, as there is in this case. I'm not sure how crucial the airbricks are in a construction this modest, but they only cost a few quid.

Airbricks allow water that accumulates under the floor to dry, so they need to be placed below floor level

As soon as you've bricked up to the doorway level, you can put the door frame in place. Once it's levelled up, the frame will provice a very good vertical reference line. As the brick courses go up, you can set angle brackets on the bricks and against the door frame, and screw into the frame from the outside. When the brackets are mortared over by the next course of bricks, they will form a very strong anchor for the frame.

The porch is essentially built around the door frame, which provides a vertical reference line in two planes

Although the door frame is above the level of the damp-proof course, it won't hurt to stand the frame on its own damp-proof layer. It's possible that water will collect on the doorstep, the top of which also is above the damp-proof course, and allow damp to rise up into the frame timber.

Almost there now...

With the door frame and starter ties in place, it's now just a case of plodding on, one row of bricks after another, measuring and levelling as you go. Because this particular porch has, in effect, only two walls (the third wall being mostly door), it's quite easy for the brick courses on each side to end up at different heights. This means that, as well as keeping the brick courses level, it's necessary to check with a level across the walls to ensure the courses are roughly at the same height. If you don't do this, when you get to the top of the building you'll find that the roof won't sit level, which will look a bit odd.
You can brick around the window frame just as for the door frame if you have it, but as my window had to be custom made (to match the style of the rest of the house), we just had to leave a gap for it and hope for the best. If there is to be brickwork above the door and/or window frames, you need to insert a lintel of some sort -- door and window frames are not designed to be able to withstand the weight of brickwork. If there's only one or two courses of bricks above the frame, a substantial timber lintel will probably suffice; otherwise you need steel or reinforced concrete.

The brickwork finally starts to take shape

Once the brickwork is more than 4-5 feet high, it's going to get difficult to reach it from the ground. At that point you need to put up some sort of work platform or scafford, even if it's only a plank rested across a pair of boxes. Ideally the platform needs to be large enough to accommodate your working stack of bricks and a pile of mortar; otherwise you'll be up and down all day fetching stuff.

Miscellaneous thoughts

In October, mortar takes a long time to cure to load-bearing strength. This means that you need to allow a couple of days, ideally longer, between finishing the brickwork and drilling into it or otherwise bashing it about. Even resting a ladder against it can be dodgy, as I discovered to my cost when I pushed the entire top course of bricks out of place with my ladder the day after finishing (or so I though) the brickwork.

One final, rather sobering, remark: if it takes two men four days to lay 500 bricks, how long does it take three dogs and a cat to fill a bath with two taps?
Well, the rate of construction works out at 7.7 person-minutes per brick. Something to bear in mind if you fancy building your own house.

Approximate costs

Bricks, delivered	£150
Sand and cement	£50
Starter ties	£40
Door frame	£40
Lintel	£10
Sundries (plasticizer, etc)	£10

Total	£300