A £400,000 scheme to help secure the future of the only house outside Scotland by architect Charles Rennie Mackintosh has been revealed.
Grade II*-listed 78 Derngate in Northampton was remodelled by the Scottish designer in 1916.
The trust in charge of restoring the house opened it to the public in 2003.
It is seeking funding from Northampton Council and other sources to expand nearby 82 Derngate to improve public facilities.
The trust uses the neighbouring 80 and 82 Derngate for displays and a shop and education centre, to help celebrate the architect who lived from 1868 to 1928.
Mackintosh is known for designing the Willow Tearooms in Glasgow and the city's School of Art, which burnt down earlier in June.
He transformed the interior of early 19th Century house 78 Derngate with his distinctive Art Nouveau style of design.
Les Patterson, company secretary of the trust, said it hoped to secure a commitment of a grant of up to £200,000 from the council which it would look to match with funding from other organisations such as the Heritage Lottery Fund.
The council's cabinet is looking at the funding application on Wednesday next week.
The plans, which are being drawn up by the trust and architects - and will eventually go before the council's planning committee - would see a bigger shop and a new mezzanine floor including space for meetings or displays.
Mr Patterson said if given the go-ahead the plans would help secure the financial future of the museum.
"We depend on trading for our existence. We believe that this plan will produce a greater income and make the venue much more sustainable," he said.