Homeowners who bought paint from B&Q earlier this year may be able to claim a refund after a flood of complaints that it made their homes smell of cat urine.

The problem relates to paint made by Valspar, which supplies an exclusive range of paints to the DIY chain.

Shoppers have reported that even if the paint had been applied in the spring and dried thoroughly, warmer weather in the summer has apparently caused a stench that some have compared to rotting vegetables... but most agree is very much like cat wee.

Valspar said the stink was caused after an additive was removed from eight of its 140 paint products earlier this year. It has now re-added it to solve the problem – although we've seen dozens of complaints on social media from those who've already painted their homes.

'A cat wee smell when you've no cat'

B&Q won't tell us how many complaints it's had from customers – it says only that it's a "small number" – but those who have complained have been vocal. Here are a few of the tweets we've seen:

Charlotte Quine, from Brighton, told Radio 4's You and Yours programme that she redecorated her spare room using Valspar paint. She said: "I assumed a cat must have got into the room through the window and sprayed everywhere. Eventually I moved all the furniture out, washed down all the walls, got some carpet cleaner, but again nothing [changed; the smell remained]."

Sarah Carter is one MoneySaver affected. She emailed: "I used annual leave time to decorate my house using the paint – some people have paid decorators. Are we expected to... take more time off work to paint it all again? Should we really just be painting over this and masking the problem before it has been investigated?"

What should you do if you're affected?

B&Q says it's dealing with complaints on a case-by-case basis, but it is offering some refunds, in vouchers or in cash. If you're affected, ring it on 0333 014 3098 or go into a store with your receipt.

A spokesperson said: "We are aware of this and would like to apologise to the small number of customers affected. We are working with our supplier, Valspar, to support our customers."

From reports we've seen it doesn't appear you'll necessarily get a full refund though. Lynn Tonks‏ said on Twitter: "Offered just £45 towards £200 cost to repaint my house after B&Q Valspar paint causes my walls to smell of cat wee!?"

Here comes the science bit...

So what exactly went wrong with the paint? In a statement Valspar said the issue was related to an additive which had been removed and since replaced.

A spokesperson said: "The ammonia-type odour occurs very rarely and when used on walls that are particularly porous, and where the wall is exposed to excessive heat or direct sunlight. The odour naturally wears off over time. We apologise for any inconvenience caused and ask that anyone similarly affected contact B&Q's customer services."