Rowhouse Pest Proofing in Baltimore, MD

Why does sealing a rowhouse matter more than in a detached house?

In an attached house, pests can enter from the outside and from the house next door. Shared walls, joists, plumbing chases and cellars create routes that no one house controls. Sealing your side reduces what can get in, but the results hold longest when neighbours deal with their gaps too.

A detached house has an outside you can walk all the way around. A rowhouse has two party walls you cannot reach and a front and back wall that face an alley or street. Mice and roaches do not respect property lines, and a technician cannot see inside a wall void that belongs to the house next door.

We cannot cite a Baltimore-specific study of how far pests travel along a row, so this is reasoning, not measurement. But it is why technicians in attached housing often ask whether the neighbours have seen the same pest, and why a one-house treatment may not hold unless the next houses are dealt with too.

What are the most common gaps in Baltimore rowhouses?

The most common openings are around pipes and drains in the cellar and under sinks, at cellar windows and vents, in cracked mortar, and where the roof meets a party wall or rear addition. Old coal chutes, closed-off flues and gaps behind radiators also turn up often in older houses.

Older brick houses have been repaired and altered many times. Plumbing has been replaced, kitchens have been extended, and walls have been opened and patched. Each of those jobs can leave a gap, and over decades small gaps become routes.

A technician will look for gaps around:

• Water, gas and drain pipes where they pass through floors and walls
• Cellar windows, vents and the cracks around them
• Mortar joints that have crumbled, especially at the base of walls
• The joint where the roof meets the party wall, and rear additions
• Door thresholds, particularly at the cellar and back doors
• Gaps behind radiators, cabinets, and bath and kitchen fixtures

Does formstone or an old facade affect pest proofing?

Formstone and other facing materials are cosmetic surfaces over brick, so they do not change the principle of sealing. But they can hide cracks, and damage behind them is not always visible. A technician looks for gaps at the ground, around windows and where services enter, and does not assume the facade is sound.

Formstone, a cement-based wall facing patented in Baltimore in 1937 by Lewis Albert Knight of the Lasting Products Company, covers many rowhouse fronts in the city. We do not claim it causes or hides pest entry. The point is that you cannot judge a wall by its surface, so the technician checks the edges where a facade meets the ground, the windows and the cornice.

Any repairs to facings or masonry that go beyond sealing gaps are work for a mason, and a technician will say so rather than patch over a larger problem.

Can I proof my rowhouse myself?

You can do some of it: change door sweeps, screen vents, seal small pipe gaps with the right materials and keep the cellar clear. Rodent-proofing needs materials that gnawing cannot defeat, and many gaps are hard to see or reach, so most owners combine their own work with a technician's inspection.

Caulk and foam alone are often chewed through by rodents. Metal mesh, steel flashing, concrete patching compound or a sealant over mesh last longer. Work in a cellar can also involve dust, cobwebs and cramped spaces, and it is worth wearing a mask and gloves.

If you rent, check your lease and talk to your landlord before you seal or patch anything. Our rental property pest control page explains how shared responsibility often works in practice.