If you are searching for masonry restoration companies to help you bring your aging brick or stone building back to life, you are likely to find a few contrasting opinions upon the best ways to treat specific problems, such as deteriorating mortar or water-saturated masonry units. It can be difficult to understand which contracting company has the right solutions, if you don’t know anything about masonry construction or the restoration process.
Contemporary and Historical Buildings
The greatest difference between restoring an historical building and a contemporary masonry structure is this:
- Historic brick and stone structures were built to absorb and release water, whereas contemporary constructions were built to be waterproof.
These two very different approaches to masonry construction weren’t simply a matter of choice – like historical builders preferred absorption and then modern builders decided to go with waterproofing. Masonry bricks in the 18th and 19th centuries were much softer than the bricks that began to be produced in the 20th century, because they were fired in kilns that were inconsistent and incapable of reaching the higher temperatures that 20th century kilns were capable of achieving.
- The hotter the fire, the stronger and more waterproof the brick. As a result, stronger bricks resulted in a change in building methods.
The Matter of Mortar
In order to accommodate their softer bricks, historical builders had to make use of softer mortars. Softer mortars are better capable of drawing water out and away from the masonry units they are supporting than the denser and more rigid mortars that are used for buildings constructed of fully fired, fortified bricks. So there is a rule of thumb: The softer the brick, the softer the mortar, and equally, on the other hand, the stronger the brick, the stronger the mortar.
- Understanding this concept is pivotal to performing a successful restoration of your masonry structure. So be sure to bring it up while you are discussing your project with various restoration companies. And, if they disagree or don’t seem familiar with this very pertinent rule of thumb, you will know it’s time to move on and look for a masonry contractor with knowledge and experience of quality restoration work.
Re-Pointing Your Property
Re-pointing is one of the most common methods of restoring masonry structures, and it entails removing crumbling or failing mortar joints and replacing them with new mortar. This is where knowing the difference between historical and contemporary building materials comes into play. Historical structures must be re-pointed using mortar that was original to the building at the time of its construction. You may think: Why use the same type of mortar, when it has obviously broken down over time and needs to be replaced? However, the importance in using matching mortar lies in its function. Lime-based mortars are softer, more flexible and water permeable than Portland cement based mortars, and because the masonry bricks used to build historical buildings are softer, they require softer mortars.
- Lime-based mortars draw water away from softer masonry units and prevent moisture from becoming trapped inside the bricks or stones. Trapped moisture will eventually freeze, expand and cause the masonry to crack, crumble or loosen.
- Softer mortars also accommodate the shifting of masonry structures, as they expand and contract due to the weather.
- Portland cement based mortars are dense and not as water permeable as lime-based mortars, which means that they will not carry water away from masonry units, but instead will cause the bricks and stones to become saturated with moisture. And this will ultimately lead to costly material damages when the water inside the masonry units freezes.
- Harder mortars are less giving. And as opposed to accommodating the natural expansion and contraction of older masonry units, harder mortars will cause them to break, crack and dislodge.
It is important that restoration companies be aware of the age of your building, before they ever even begin their work. If they never discuss mortar analysis with you, you should be leery of their abilities to perform your restoration. Matching mortar is one of the most crucial steps to ensuring that your property will endure the tests of time.
If you are researching restoration companies to bring your masonry-built property back to its former glory, be sure to ask if they are aware of the importance of mortar matching. It will be your first indication of whether or not you are working with a company that cares about the work that they do.