Rodent proofing in Cardiff homes is about stopping the problem at the source. Traps and bait deal with the mice or rats already inside, but if the gaps they used are still open, more will follow, especially as the weather turns cold. We find those entry points, seal them with materials rodents cannot chew through, and clear up the mess they leave in the loft.
To be clear about what we do: we focus on proofing and cleanup. We do not lay poison or bait. If there is an active infestation, we can work alongside your pest controller, with them dealing with the rodents and us making sure they cannot get back in.
Signs of mice or rats in the loft
Most people find out about mice in the loft by hearing them. Other signs to look for:
- Scratching or scurrying at night, in the ceiling above bedrooms or inside walls.
- Droppings on boards, on top of the insulation or around the water tank. Mouse droppings are small and dark like rice grains; rat droppings are much larger.
- Gnawing on timber, boxes, pipe lagging or plastic.
- Chewed cables. This is a real fire risk, and any damaged wiring should be checked by an electrician.
- Flattened, tunnelled or shredded insulation, often with runs along the joists.
- A stale, ammonia-like smell in the loft or upstairs rooms.
Our guide to the signs of rodents in your loft covers how to tell mice from rats and what to check first.
How rodents get into lofts
Mice can squeeze through remarkably small gaps, roughly the width of a pencil. Rats need bigger openings but are strong chewers. In Cardiff homes, the common routes in are:
- Eaves and soffits. Gaps where the soffit boards meet the wall, loose or rotten fascias, and missing eaves combs or bird guards.
- Pipe and cable penetrations. Where water pipes, overflows, gas pipes, cables and satellite leads go through the outside wall.
- Gaps around soil stacks and vent pipes, both where they pass through walls and where they enter the roof.
- The cavity. In cavity-walled houses, rodents can climb inside the cavity and come up into the loft at the wall head. Open weep vents and damaged air bricks lead into it.
- Party walls in terraces. In older terraced streets, gaps in the shared loft walls can let rodents travel between houses.
- Damaged roof covering, such as slipped tiles, gaps at the verge, or worn mortar at ridges.
Why problems often start in autumn
Mice and rats look for shelter and warmth as the weather turns colder, and a loft full of soft insulation is ideal for nesting. That is why many people first hear scratching in the ceiling in autumn and early winter. Gardens backing onto lanes, bins, compost heaps, bird feeders and nearby watercourses can all bring rodents closer to the house, but it is the gaps in the building that let them inside.
Mice breed quickly, so a few in the loft can become many if nothing is done. Proofing early, ideally as soon as you notice signs, keeps the job smaller and saves more of your insulation.
How we rodent-proof a home
A full inspection
We start in the loft, following droppings, runs and gnaw marks back to where they lead. We then check the outside of the house at the eaves, soffits, pipe runs, air bricks and soil stack. The aim is to find every likely entry point, not just the obvious one, because sealing one gap and leaving another does not work.
Sealing entry points
We use materials that rodents cannot chew through:
- Galvanised wire mesh for larger gaps at eaves and soffits, and around vents where airflow must be kept.
- Steel wool packed into gaps around pipes and cables, then sealed over.
- Mortar to fill holes in brickwork and around pipe entries.
- Purpose-made covers and guards for air bricks and weep vents, so ventilation is kept while rodents are kept out.
Expanding foam on its own is not a rodent barrier. Mice and rats chew straight through it, which is why it so often fails as a DIY fix.
Keeping ventilation open
A loft needs to breathe. Blocking eaves and air bricks solid would stop rodents but lead to condensation and damp. We use mesh and guards that keep air moving. If a loft is already damp, see loft mould treatment.
Replacing contaminated insulation
Rodents nest in loft insulation, tunnel through it and leave droppings and urine in it. Once it is soiled, it smells, it can carry disease, and it is often flattened so it does not insulate well either. Topping up over the top just buries the problem.
We bag up and remove the contaminated insulation, clean down the area, and re-lay new loft insulation to 270mm. We do this after the entry points are sealed and any active infestation has been dealt with, so the new insulation stays clean.
Working alongside pest control
If you still have rodents in the loft, they need dealing with by a pest controller first or at the same time. We are happy to coordinate with yours. The usual order is: pest controller treats the infestation, we seal the entry points, then once activity has stopped, we strip and replace the insulation. Doing the proofing promptly also stops new rodents from replacing the ones removed.
What affects the cost
Rodent proofing starts from £250. The price depends on:
- How many entry points there are and how easy they are to reach. Work at high eaves may need access equipment.
- The type of house. Detached homes have more exposed perimeter; terraces may have party wall gaps.
- How much insulation needs stripping and replacing.
- Any repairs to soffits, fascias or brickwork needed before sealing.
What happens on the day
We protect the landing and set up in the loft. Entry points identified at the survey are sealed inside and out. Where insulation is being replaced, it is bagged in the loft and carried out, the area is cleaned, and new insulation is laid. We tidy up and talk you through each sealed point and the finished loft.
Aftercare
- Keep an ear out for noises over the following weeks and let us know if activity continues.
- Do not store food, bird seed or pet food in the loft.
- Ask other trades to tell you if they make new holes through outside walls.
- Check outside at the eaves after storms for damaged soffits or fascias.
We cover Cardiff and the surrounding towns. See all the areas we cover, or call 0800 229 4668 to book a free survey.