Matching Brick Colour, Size and Texture on a Part Rebuild

What the eye actually compares

People assume matching means finding the same shade, but a viewer standing on the pavement is reading several things at once. The first is the overall tone of the stack against the roof and the house below it. The second is the pattern of the courses, meaning how the joints line up and how thick they look. The third is the surface: whether the faces are soft and slightly irregular or crisp and flat. A brick can be spot on for colour and still look wrong because it fails the other two.

Contrast is what draws attention. A new head that is a touch lighter than the old stack will often pass unnoticed, because roofs and chimneys carry plenty of natural variation. A new head that is perfectly uniform sitting on a stack where every brick differs from its neighbour will not pass, however close the average colour is. The same applies to the joints. A smooth, bright, freshly struck joint reads as a different material from a recessed, weathered one, even when the brick is right.

Reclaimed brick is also variable by nature, so what a supplier calls a red or a buff can cover a wide spread. That is not a drawback when matching an old stack, since the old stack has the same spread. Ask for the range, not the average.

Size, gauge and why a few millimetres matter

Old bricks were made by many small makers to no single standard, and a modern merchant's brick is a fixed metric size. When you lay one on top of the other, the courses of the new work no longer line up with the courses of the old, and the joint thickness has to be adjusted to compensate. The eye notices a change in gauge at the junction more readily than it notices a change in shade, because the horizontal lines are the strongest feature of a chimney.

The practical check is to measure a few of the existing bricks, including the depth, and to measure the height of a run of courses. A reclaimed brick of the right period is often close in size as well as character, which is one reason it is the usual choice for a part rebuild. If no brick of the right size can be found, the next best approach is to keep the gauge steady across the whole of the new work and make the change in a place where it is hidden, such as the line of the lead or the back of the stack. Fattening every joint to catch up is the thing to avoid.

Sampling: how to judge a brick before it goes up

A single brick held in the hand tells you very little. Ask for several bricks from the batch, and ask to see them laid out dry against the stack or beside a sound part of the same wall, outdoors, in ordinary daylight. Bricks look different under cloud and in low sun, and they look different wet and dry, so look at them in the conditions the house is usually seen in. Wet brick is darker and richer, which is flattering and misleading; judge the sample when it has dried.

A better test than any single brick is a small panel, a few bricks laid in a bed of mortar with the joint finished to the profile of the original, left to stand against the stack. That shows the combination of brick, mortar and joint together, which is what the street will see. Pick the sample that sits comfortably against the old work, not the one that is cleanest. The aim is for the eye to slide over the junction, not to stop at it.

These tests cost nothing but patience, and they are worth the delay. The cost of a wrong brick is paid every day it is seen, long after the scaffold has come down. If the sample board looks acceptable only when you stand close and squint, it is not right.

Using the bricks that come off

On a part rebuild the best matching material is already on site. The bricks taken down from the head were made for this stack and have weathered with it. Where they are still hard and the faces are intact, they can be cleaned of old mortar and re-laid on the visible faces, with new or salvaged brick used for the back, the inner skin or the courses below the lead. Not every brick will survive the process, because the top of a stack is where frost and flue gases do most damage, so expect to need extra brick to make up the numbers.

This is why it is worth asking for the old bricks to be sorted rather than skipped away at once. A sound brick that has lost a face to frost can sometimes be turned and used with its good face out. The ones that crumble when tapped are discarded. A competent bricklayer will do this sorting as the stack comes down, and it is a sensible thing to raise at the quotation stage. The wider decision about whether to repoint, rebuild or remove is covered in Repoint, Rebuild or Remove? How the Decision Gets Made.

Where matching reaches its limit

There are things no brick can fix. Weathering takes a long time and it is not even: the stained, lichened and sun-faded surface of the old work will stand apart from new brick for a good while, and in some cases it will never fully close the gap. Handmade bricks fired in old kilns have flashes and colour ranges that cannot be reproduced exactly, and if the original brick was a one-off local product there may be no true equivalent anywhere. Honest advice at the outset is that the result will be a close match, not an invisible one.

What you can control is the quality of the compromise. Choose the right size first, then the surface, then the colour range, and keep the pots and the lead looking as though they belong. Roofline Solutions covers the outside of the stack across the peninsula, and the chimney repairs in Wirral page explains how a part rebuild is carried out. If you are unsure what you can see from the ground, What to Look For on a Chimney From the Ground will help you describe it before anyone visits.