My husband and I got a REAL sofa set and chair, and were thinking instead of getting rid of the Ikea couch we had, we might be able to put it outoors. I can't find a link to the couch, but it matches this chair: http://www.ikea.com/us/en/catalog/products/S19830526 , same in terms of materials. Would the wood be safe from warping if we treated it with something? And all the pillow cases come off. How do we find new ones to fit that are waterproof?