The Problem
This 1925 Tudor Revival is one of Kenilworth’s finest historic homes. A contractor in the 1990s had repointed the front facade with standard Portland cement mortar - a common mistake on pre-war homes that causes serious long-term damage.
The Portland mortar (compressive strength ~2,500 PSI) was far harder than the original lime mortar (~300 PSI) and the soft handmade brick (~1,200 PSI). Physics dictates that the softest material in the wall assembly absorbs the stress from thermal movement and moisture cycling. With Portland mortar, the brick became the weakest link. Over 25 years, the trapped moisture and rigid mortar had caused spalling on 40+ bricks across the front facade.
The homeowner was referred to us by a local preservation architect who knew we work with traditional lime mortars.
Our Solution
This project required a fundamentally different approach from standard tuckpointing. We used NHL 3.5 (Natural Hydraulic Lime) mortar - a material that sets through both carbonation and hydraulic reaction, making it appropriate for exterior use in wet climates while remaining soft enough to protect the original brick.
All Portland cement mortar was carefully removed from the front facade joints. This required hand tools exclusively - no power grinders, which risk damaging the soft, irregularly shaped handmade brick. Removal took three days alone.
The NHL 3.5 mortar was blended with washed sharp sand in a 1:2.5 ratio, matched to the original mortar’s aggregate profile. A small amount of brick dust was added as a pozzolan and to achieve the warm pink-gray tone of the original 1925 mortar.
Lime mortar requires different curing than Portland-based mortar. We protected fresh joints from direct sun and wind with damp burlap for five days after application. Lime mortar carbonates slowly - it takes months to reach full strength - so this protection during the critical early cure period is essential.
The 40+ spalled bricks were left in place. With the correct lime mortar now absorbing stress instead of the brick, the spalling will not progress further. The damaged faces add character consistent with the home’s century of history.
The Result
The facade now has historically correct mortar that works with the original building materials rather than against them. The lime mortar will allow moisture to migrate through the joints as designed, protecting the irreplaceable handmade brick from further damage.
The homeowner and their preservation architect inspected the completed work and confirmed the mortar color, texture, and joint profile match the original 1925 work in the protected side passages.
