Warranty Policy
One Third 10-Year Guarantee
At One Third, we are proud of the engineering, materials, and testing that go into every mattress we make. Our mattresses are delivered flat and unrolled to help preserve their structure, comfort, and long-term performance.
To give you confidence in your purchase, every new One Third mattress comes with a 10-Year Guarantee against manufacturing defects.
1. How the Guarantee Works
Your One Third mattress is guaranteed for 10 years from the original date of delivery.
If your mattress develops a manufacturing fault during this period and the issue is covered under this policy, we will arrange for the mattress to be repaired or replaced, depending on the nature of the fault and the outcome of our assessment.
If the original mattress model is no longer available, we will provide the most comparable current model.
This guarantee applies only to genuine manufacturing defects and does not cover normal wear and tear, accidental damage, misuse, or issues caused by an unsuitable bed base.
2. What is Covered
This guarantee covers manufacturing flaws and structural defects that occur during normal everyday use. This includes:
Significant sagging
A visible indentation or sag in the mattress surface greater than 2.5cm, provided it is not caused by a faulty, damaged, or unsupportive bed base.
Foam or spring failure
A physical flaw that causes the foam to split or crack, or the pocket springs to fail, despite normal use and proper handling.
Cover defects
Manufacturing defects in the zipper assembly or mattress cover fabric. Cover defects are covered for the first 2 years only.
3. What is Not Covered
This guarantee does not cover normal wear and tear or damage caused by use, handling, storage, or the surrounding environment. It excludes:
Normal softening
A natural increase in softness over time, provided the mattress still offers normal comfort and support.
Comfort preference
A change in personal comfort preference after the 365-night sleep trial has ended.
Improper support
Damage caused by using the mattress on an unsuitable bed frame, foundation, or slatted base. Slats must be no more than 7.5cm apart and must provide strong, even support.
Physical damage
Burns, cuts, tears, stains, liquid damage, or other accidental damage. We strongly recommend using a mattress protector.
Environmental damage
Mould, dampness, odours, or damage caused by poor ventilation, spills, bodily fluids, or unsuitable room conditions.
Second-hand purchases
Mattresses bought used, “as-is,” or from unauthorised third-party resellers. This guarantee is valid only for the original purchaser.
4. Important Requirements
To keep your guarantee valid, your One Third mattress must be placed on a suitable base from the first day of use.
Because our mattresses are heavy, high-quality, and delivered flat, they require a firm, stable, and supportive foundation. Suitable bases include divan bases, solid platform frames, or strong slatted frames with proper centre support.
If we determine that the mattress fault was caused by an inadequate or unsuitable foundation, the guarantee claim may be declined.
5. How to Make a Claim
If you believe your mattress has developed a fault covered by this guarantee, please contact our team.
Email: hello@one-third.co.uk
with the subject line:
Guarantee Claim – [Your Order Number]
Please include:
- Your original order confirmation or receipt
- Clear photographs of the issue
- For sagging claims, a photo showing a straight edge, such as a broom handle, placed across the mattress with a ruler measuring the depth of the dip
Our Sleep Specialists will review your claim within 3–5 working days and contact you with the next steps.
One Third Support Team
Email: hello@one-third.co.uk
Hours: Monday – Friday, 9:00 AM – 5:00 PM
Address: Unit 2 Day Street, Dewsbury WF13 3LJ