Under the trial, valuers still visit the property to inspect it, but do not enter the home.
It comes as many lenders, Leeds BS included, resume physical valuations this week.
Most lenders had only been carrying out desktop and automatic valuation models since March when the UK went into lockdown.
However, the mutual said it recognised many people were still concerned about external visitors in the home during the current climate.
Jaedon Green, chief customer officer, said: “We’ll complete desktop valuations to ensure we maximise capacity for physical valuations.
“Where a desktop isn’t appropriate, we’ll try to complete a full physical valuation, although most structural issues can typically be identified externally.
“However, we appreciate we’re living in a complex world, especially for homeowners and our customers, who may be isolating for medical reasons, shielding, or concerned about risk, despite valuer precautions such as the use of personal protective equipment (PPE).
“For those reasons, we’re working with Countrywide, using a physical external valuation where that’s sufficient to give the necessary confidence on valuation for the loan requested.”