Brick Mortar - Type N Mortar Concentrate

"Type N" is a specific classification for mortar designated by the American Society for Testing and Materials (ASTM) in its masonry mortar standard, ASTM C270. It refers to a medium compressive strength mortar (a minimum of 750 psi at 28 days) made from a balanced blend of Portland cement and hydrated lime.

That medium strength is the point. Type N is strong enough for everyday modern brick, stone and block, without being so hard and rigid that it fights the masonry around it the way a higher-strength mortar can.

Our ProMason Type N Mortar Concentrate is made to the ASTM C270 proportion specifications for Type N mortar, using industry-standard proportions, and is designed to meet or exceed the strength for Type N mortar.

Type N is the mortar for modern masonry. From about 1950 on, Portland cement-lime mortars became the standard, and Type N became the everyday mortar for brick and stone walls. If your building was built after about 1950, and the existing mortar is Portland-based (hard, gray and concrete-like, where a key or the edge of a sharp tool barely marks it), Type N is very likely the right match.

For older buildings, start earlier in our line:

• Before about 1920: a PHL lime mortar (most often PHL 3.5).
• About 1920 to 1950: Type O.

The golden rule of masonry repair still applies: the repair mortar must be softer than the brick or stone it joins, and no harder than the original mortar.

A simple do-it-yourself check before you do the whole wall: break open a loose piece of the old mortar to see its true color and sand, away from the weathered face. Then mix a small batch, point a few joints somewhere out of sight, let them cure, and compare the new joints with the old ones once they're fully dry.

Type N is a cement-lime mortar: it contains both lime and Portland cement, in the proportions set by ASTM C270 for Type N (roughly equal parts Portland cement and hydrated lime). The lime adds workability and helps the joint handle moisture, while the Portland cement gives it the medium strength a modern wall needs.

Because it contains Portland cement, it is not a lime mortar like our PHL mortars, which contain no Portland cement.

No. Repointing is its most popular use, but Type N is a general-purpose mortar and can also be used for:

• Laying brick, stone and block: building or rebuilding walls, piers and veneer in modern masonry.
• Setting sills: bedding stone, brick or precast sills.
• Steps: repointing or resetting brick and stone steps where the existing mortar contains Portland cement. (If the existing step mortar is a traditional lime mortar with no Portland cement, use PHL 5.0 instead.)

In every case, match the mortar to the existing work: Type N belongs where the original mortar already contains Portland cement. Type N isn't for paving patios or walkways.

Yes, a final cleaning is an important last step to achieve a professional and tidy finish. It removes the mortar haze, smears and splatters that happen during repointing, and restores the clean, sharp look of the brickwork.

It is vital not to use harsh, aggressive acids (like muriatic acid), which can damage the new mortar joints and the face of the brick.

This is why we developed Pro Mason Mortar Wash. It is a gentle masonry cleaner formulated to dissolve fresh mortar haze and stains without attacking the joints or the masonry. Following the product directions, use it with a soft-bristle brush and a low-pressure rinse to put the finishing touch on your project.

Yes, removing the old, deteriorated mortar to a proper and uniform depth is a key step for a long-lasting repointing job.

The industry-standard guideline is to remove the old mortar to a depth of 2 to 2.5 times the width of the mortar joint.

For example, for a common 3/8" wide mortar joint, excavate the old mortar to a depth of at least 3/4" to 1". A plugging chisel is a useful tool for this.

Why is this depth recommended? It gives the new mortar enough surface area to create a solid mechanical bond and lock itself into place. A shallower application may not be as durable and can be more prone to early failure from weather and freeze-thaw cycles.

Keep removing old mortar until you reach a solid, sound base, even if that is deeper than the guideline. Take care not to damage the edges (arrises) of the brick or stone.

Yes. Type N gains its strength as the Portland cement hydrates and the lime slowly cures, and both need moisture. If the joints dry out too fast, they won't reach their full strength. For the best results:

• Keep it damp: lightly mist the new joints with water daily for at least 3 days. Damp burlap helps hold the moisture in.
• Protect from weather: shield the wall from intense sun, high winds and heavy rain while it cures.
• Avoid freezing: protect the work from freezing for 1 week after application. Plastic sheeting can be used for light frost protection at night during this time.

Yes, but match the sand you mix with our concentrate to the joint size. Mix 1 part Type N concentrate with 2.5 to 3 parts clean sand, then add water gradually until the mortar is smooth and workable. The general guideline is that the largest sand grain should be no more than one-third of the joint's width.

• For narrow joints (under 3/8"): mix our concentrate with a fine masonry sand (such as ASTM C144) to ensure a tight, complete fill.
• For wide stone joints (over 3/4"): mix our concentrate with a coarse, well-graded sand. This gives the mortar the stability it needs and helps control shrinkage in larger gaps.

Yes. Type N mortar can be used for brick, stone and concrete block projects.