The main disavantages of a pwf foundation when the foundation is backfilled over 48" it need a custom design. Because of this , you may save 3 or 4 hundren dollars on your materials and labor if pwfs.com designs the foundation system. Only a custom design can save you money. If you build the pwf system with out any design, it will cost your more at the time or repair. Why pay more? have it designed, Yes , A panel foundation must be designed too. I talk to a designer at a training class, his name is Roscoe Clark. You may call him for more infomation at 810 232-5099 of see the Official web site call woodbasement.com thanks PT Installers.