Tuckpointing fireplace masonry is an indoor job that might also require you to consider, if exposed and accessible, tuckpointing the chimney masonry above the fireplace and outside.
Tuckpointing fireplace masonry is important because, apart from keeping the masonry looking tidy and clean you need to reduce any risk of fumes from the fire escaping into your room, or indeed any uneven draughts developing in the fire itself.
Before you Start Tuckpointing
Whilst any damaged fireplace mortar will need replacing the whole appearance of your fireplace can be improved by tuckpointing all of it. This will especially be a good idea if you need to replace any damaged pointing. The chances of you being able to mix a mortar to exactly the same color as the original mortar are, after all, slim at best.
A recommended mixture for your mortar is 1 part of Portland cement to 8 parts of silver sand. Silver sand is preferred it has a higher heat resistance. If you should want to create a particular colored effect with your pointing, then when buying the cement and sand ask your builders merchant or DIY store for the cement coloring of your choice.
As well as needing a trowel to apply the mortar other tools you’ll need include a hawk, a stiff bristled brush, an old narrow chisel or file, a damp cloth and possibly a recessing implement; as your tuckpointing can be done flush to the brickwork or recessed into it.
How to Tuckpoint a Fireplace
With the fireplace cold – the first thing to do is to remove the old mortar, scrape away at the surface of the mortar with something like an old chisel or file that is narrow enough to fit in between the bricks. Then brush vigorously all over the fireplace surface to remove all the loose material; don’t forget before applying the new mortar to wet the brickwork and old pointing. Having mixed your mortar transfer some of it onto your hawk and then pick some of it up on the back of your trowel.
Press the mortar firmly into the vertical joints first and then into the horizontal joints above and below where you’re working. At this point you want the mortar to be flush with the brickwork surface. If you want to keep the flush joint, then simply wipe off any excess mortar on the bricks and smooth down the tuckpointing, with the damp cloth.
To make a V joint, holding it steady in both hands if necessary, place the point of the trowel in the center of the mortar, press down and draw the trowel along or down the mortar joints. Alternative recessing effects can be achieved with a variety of implements.
A concave pointing joint can be created by pressing a curved object, like a bucket handle, into the mortar, whereas a sloping recessing effect on the pointing can be created by angling a narrow piece of wood and running it across and down the mortar. Don’t forget to wipe off any mortar that gets spread onto the brick work as a result of recessing the tuckpointing.
If at all possible do leave the mortar for at least 24 hours to dry out and set properly. Lighting a fire in the fireplace too quickly could cause the mortar to dry out to rapidly and crack, meaning that you’ll have to repeat the whole process.