Achieving Aesthetic and Structural Brick Compatibility in Construction Projects

The Challenges of Matching Old Bricks

When undertaking any construction or renovation project involving brickwork, one of the biggest challenges is often finding replacement bricks that match the existing ones. This is especially true when dealing with older bricks that may no longer be commercially manufactured.

Why Matching Bricks Matters

Matching old and new bricks is important for both aesthetic and structural reasons. Aesthetically, mismatched bricks simply look bad and detract from the overall appearance of a building or structure. Using bricks of noticeably different sizes, shapes, textures or colors next to one another looks disjointed and unprofessional.

Structurally, new bricks need to match the capabilities and specifications of the surrounding bricks they are paired with. Using a softer or more porous material next to an existing harder brick surface could lead to weathering problems down the road.

The Causes of Color Variation

There are a few key reasons why new replacement bricks might not match existing brick surfaces:

• Natural material variations - Clay deposits used in brick manufacturing have natural variances.
• Manufacturing process changes - Formulations and baking temperatures impact color.
• Weathering over time - Long term sun/rain exposure alters brick color.
• Batch differences - Brick manufacturers produce bricks in batches that can vary.

These differences mean that even with the original manufacturer's brick type, there can be noticeable variation between new and old bricks.

Options for Matching Old Bricks

When replacement bricks don't match, there are several options to consider:

1. Try ordering more bricks - Getting bricks from the same batch as existing bricks can sometimes yield a match.
2. Use weathering techniques - Artificially weathering new bricks can help them blend better.
3. Consider alternative materials - Another material like architectural stone may match better.
4. Paint or stain bricks - Applying color treatments can effectively disguise color differences.
5. Embrace the difference - Sometimes mismatching bricks end up looking interesting.

The best approach depends on several factors - budget, project scale, aesthetics and time constraints on the project. Often trying multiple matching techniques yields the best result.

Techniques for Weathering Bricks

One of the most effective ways to help blend new replacement bricks into an existing weathered brick wall or structure is through artificial weathering techniques. The goal is to recreate the aging effects that natural weatherization has produced over the years.

Here are some manual approaches to artificially weather bricks:

Acid Solutions

Applying acidic compounds to the surface of fresh bricks helps pull out minerals and recreate the patina of aged bricks. Some common household products to experiment with include:

• White vinegar - Helps dissolve alkaline compounds in bricks to expose more texture.
• Citric acid mixtures - Sold commercially for superficial aging of new masonry.
• Oxalic acid solutions - Reacts with iron compounds in clay to add darker rust staining.

Various acid concentrations and dwell times yield different effects. Test samples help identify the ideal brick weathering acid formulation.

Wire Brushing

Using a wire brush or wheel on bricks literally erodes away the brick surface slightly to make bricks appear older. This also serves to expose more of the aggregate in concrete bricks. Different wire brush grades remove material rapidly or more gradually.

Heat Application

Heating bricks with a blow torch or other concentrated heat source leads to expansion and subsurface cracking that mimics weathered, aged brick. Use caution when applying direct heat and supervise the heating process closely.

A combination of manual and heat aging approaches often work best to match old brick. Always test any brick weathering methods first on spare bricks rather than jumping right on installed bricks.

Achieving Structural Compatibility with Old Bricks

While color, texture and appearance compatibility should be prioritized when sourcing matching bricks, the structural integrity of masonry projects also requires consideration.

Mortar Selection

Ensure the hardness of selected mortar matches what is used on existing, adjoining bricks. Using extremely hard mortar next to crumbling, soft old mortar can lead to stability issues and cracks during settlement. Mortar compressive strength is measured in PSI ratings.

Replacement Brick Density

Try to identify or estimate the density/hardness values of bricks being matched to. Refractory ratings provide this data. Replacing soft bricks with extremely hard, dense bricks risks stability - lighter bricks may settle differently over time.

Water Absorption

The rate at which the original and replacement bricks absorb moisture should be similar. If not, differential weathering can slowly degrade brick bonds and integrity. Check product spec sheets for water absorption performance metrics.

Conducting custom material strength testing may be warranted for large scale masonry jobs. Always consult an engineering professional if any doubt exists on structural fitness.

With some diligent sourcing effort and aesthetic weathering tricks, the challenge of matching old bricks can be overcome. Proper brick selection preserves both the appearance and structural soundness of buildings and brick features.

FAQs

What's the easiest way to identify replacement bricks that match existing ones?

The best approach is to contact the original manufacturer and order new bricks from the closest production run batch. This yields the best color, texture and size match if records are available.

Can I just paint or stain mismatched new bricks instead?

Yes, applying compatible brick paints or opaque stains can effectively disguise color differences between old and new bricks. Proper surface preparation and sealant choice helps achieve long lasting results.

What if replacement mortar doesn't match the old mortar?

Recreating the same mortar composition, proportions, color and hardness level is ideal. But if not feasible, ensure any new mortar is at least equal or softer in hardness to existing mortar to prevent cracking issues.

How long does artificial weathering of bricks take?

The duration depends on technique and desired effect. Simple acid washes work in minutes while repeat wire brushing and torch heating cycles may take weeks to approximate aged, weathered brick.