The short answer
No, not properly. Roof felt, or underlay, sits between the rafters and the battens, directly beneath the tiles, so the tiles and battens have to come off to replace it. What can be done is a partial strip: lifting only the affected area, renewing the underlay there and relaying the same tiles. Work from the loft side can monitor and ventilate, but it cannot renew the felt.
Where the felt sits, why the tiles must be lifted to reach it, and what you can do if only part of the roof is affected.
Why the felt cannot be reached from inside
Underlay is laid over the rafters, the sloping timbers of the roof, and the battens are nailed on top of it, through to the rafters. The tiles then hang from the battens. That puts the underlay in a sandwich under the batten layer, and the only way to get at it from the loft would be to take the whole roof apart from below.
You can still look at it. A torch shows the underside of the felt between the rafters, and you may spot sagging, tears, dark patches or daylight. But you cannot pull it out, slide a new roll in or fix it from there. Any suggestion that felt can be renewed from inside, with no tiles lifted, deserves a hard question, because the battens and nails pin the old felt in place.
That is why a leak from torn felt is a roof job rather than a loft job. Our answer on torn roof underlay explains how felt fails and what each failure looks like from inside.
What a partial strip involves
If the damage is confined to one area, such as the patch above a leak, a roofer can strip just that section. The tiles are lifted, kept in order, and the battens come off. The old felt is trimmed back to sound material, and new underlay is laid with a generous overlap onto the old, which means rain sheeting off the slope passes over the join instead of finding a way beneath it. Battens go back, then the tiles, with any cracked ones swapped for matches.
A partial strip is worth considering when the rest of the roof is in good order, the tiles are sound and the felt elsewhere is intact. It is less sensible when the felt is the same age everywhere, because the next patch is simply the next area waiting to fail.
The size of the strip also shapes the access. A patch low on a bungalow can sometimes be reached from a ladder or roof ladder, while a patch high on a two-storey slope calls for a tower or scaffold. Read each quote for VAT and for scaffold hire, and expect a firm figure only after someone has been up to look, not from a phone call alone. Where the work is a single small patch, the access method often decides the price more than the felt does.
Loft-side measures and what they can do
There are things worth doing from inside, as long as nobody expects them to replace felt. A roofer can study the underside of the underlay for sag and tears, test battens for damp and decide how much of the roof to open up. Ventilation can be improved so condensation does not wet the felt from below; our answer on loft condensation and roof ventilation covers the basics.
Spray foam is sometimes pitched as a shortcut for a worn roof. The Energy Saving Trust advises against putting foam onto a roof that is still leaking, and RICS suggests asking your mortgage provider whether their policy permits such products. Foam stuck to the underside of a roof can also make later inspection of the felt and battens much harder.
A temporary patch from the loft, such as a tray under a drip, may buy a little time. It does not mend the felt, so treat it as a stopgap and arrange the proper repair from outside. Photograph any staining as it develops, so the roofer can see how the leak has behaved over the weeks.
Felt, breather membrane and your choices
When the felt is renewed, you also choose what replaces it. Traditional bitumen felt is one option and breathable membrane another; our answer on breathable membrane versus roofing felt sets out the difference. Marley's note on BS 5250 says an old-style non-breathable underlay in a cold roof calls for a 25mm gap at the eaves when the pitch is 15 degrees or less, and 10mm when it is steeper, so the membrane you pick changes the ventilation the roof must be given.
Re-covering also raises a question about weight and building control. If the new tiles will weigh more than the old ones, Planning Portal points to a surveyor or engineer for a view on the loading before the work starts. Relaying the same tiles on new felt leaves the load exactly as it was, which keeps things simple.
Our pitched roofing work covers all of this. We inspect the felt and battens, email you pictures of the condition we reach, and write down one overall price for a partial strip or for a full re-cover, so each route is laid side by side before you decide anything.
More on this in Pitched Roofing Services in Crawley
Two more underlay questions
How do I know whether my felt has failed?
Look from the loft for damp or darkened patches on the felt, sagging between rafters, tears, or daylight at the edges. Outside, look for slipped tiles and stained ceilings below. None of these is conclusive alone. A roofer lifting a few tiles will show the felt's real condition and photograph it for you.
Is it worth a partial strip if the felt is old everywhere?
Often not. Old felt tends to fail in many places over time, so a patch buys a few seasons while the rest keeps ageing. If tiles and battens are sound, stripping and relaying the whole slope while access is already in place can cost less than repeated smaller visits. Ask for both options priced.