- Best For: Replacing an old Velux, insulating a roof, or fitting new plastic windows and doors
- Based In: Berlin, ships across Germany and to Austria
- Brands: Velux, Fakro, Roto, plus own-label insulation and windows
- Shipping: About 7.50 euros for small parts, 49.90 euros for a roof window by freight
- Payment: Invoice, PayPal, card, financing, prepayment
- Reviews: Around 720 on Trusted Shops, most of them five stars
A Building Merchant That Happens to Sell Online
Perfekt-Bau is not a marketplace. It's a Baustoffhandel, a building supplies merchant, with an address on Triftstrasse in Berlin, phone hours on weekdays, and a website that sells what the yard sells. Roof windows are the specialty. Insulation is the second. Then the things you need to finish an attic: plastic windows, interior doors, stairs, blinds, and flashing kits. That matters for how you should use it. You can call and ask a question and get a person who knows what an Eindeckrahmen is. That's rare on the internet.
What Perfekt-Bau Sells, With Real Prices
| Category | Examples | Price Range |
|---|---|---|
| Roof windows | Velux, Fakro, Roto, PVC and wood | About 400 to 1,500 euros |
| Replacement packages | Fakro window plus flashing to replace an old Velux | About 790 euros for a 64 x 103 |
| Roof exits and smoke vents | Fakro PWP, FSP | 770 to 1,500 euros |
| Insulation | Mineral wool, PIR, between-rafter and on-rafter | By the pack or pallet |
| Plastic windows | Made to measure, double or triple glazed | Quoted |
| Interior doors and stairs | Standard sizes and loft stairs | Varies |
| Accessories | Blinds, awnings, control rods, roller shutters | 25 to 500 euros |
The replacement packages are the reason most people find the site. An old Velux from the 1990s has a code on the frame. Perfekt-Bau sells Fakro units sized to drop into that opening, flashing included, and triple glazing standard. That's a big saving over a like-for-like Velux, and the reviews say the fit is right when the code is right.
Insulation is the other volume seller. Between-rafter mineral wool, PIR boards for on-rafter, vapour barriers, tapes. The site sells by the pack and by the pallet, and pallet pricing is where a whole-roof job gets cheaper. 
Ordering a Replacement Roof Window From Perfekt-Bau Without a Mistake
This is where the site rewards care.
- Find the type plate on your old window. Usually the top edge of the sash. It gives the model and size, like "VL 033 64 x 103."
- Match that code to the replacement package on the site. The listing names which Velux codes it replaces.
- Check the roofing material. Flashing kits differ for tile, slate, and flat sheet.
- Decide on glazing. Triple is standard on most packages and worth it.
- Add the blind or roller shutter now. Retrofitting later costs more.
- When it arrives, unpack and check every part against the list before the roofer removes the old window.
That last step is the one a Trusted Shops reviewer wished she'd done. A short flashing piece was discovered mid-install, after the old window was out. Check before, not during.
Shipping, Payment, and Returns at Perfekt-Bau
| Detail | What to Expect |
|---|---|
| Small items | DPD parcel, about 7.50 euros |
| Windows and pallets | Freight, about 49.90 euros, driver calls to arrange |
| Austria | Available, higher freight |
| Delivery time | Stock items in days, made-to-measure in weeks |
| Payment | Invoice, PayPal, card, Sofort, financing, prepayment, cash on delivery |
| Buyer protection | Trusted Shops guarantee on eligible orders |
| Returns | Standard withdrawal on stock goods; made-to-measure items are excluded |
Invoice payment and financing both exist, which is unusual for a merchant this size. Financing on a full roof window order can make sense if the alternative is delaying the job into winter.
Freight is the part to plan. The driver delivers to the curb, not up the stairs. Have two people home, and a dry place to store a window until the roofer comes. 
Get a Quote
What Customers Report
The Trusted Shops summary from about 720 reviews reads like this: fast, punctual delivery, quality as described, cheaper than the brand-name equivalent, and staff who help before and after the sale. Several reviewers say the instructions were clear enough for a competent DIYer. The smaller group of critical reviews mentions two things. Delays where the shop didn't say why, and difficulty getting through to someone when a complaint was open. Both are easier to handle if you order early and put questions in writing so there's a record.
Perfekt-Bau vs. Bauhaus vs. Buying From Velux Direct
| Parameter | Perfekt-Bau | Bauhaus or OBI | Velux Direct |
|---|---|---|---|
| Roof window brands | Velux, Fakro, Roto | Velux, some Roto | Velux only |
| Replacement packages | Yes, Fakro into old Velux | Limited | Like-for-like, pricier |
| Advice | Specialist, by phone | General store staff | Brand hotline |
| Price | Low to mid | Mid | High |
| Delivery | Freight to your door | Store pickup or delivery | Through installers |
| Best for | Replacements and attic projects | One window, quick | Exact brand match |
If you want the cheapest good replacement, Perfekt-Bau. If you want to walk out with a window today, a big-box store. If the roofer insists on Velux, buy Velux.
Frequently Asked Questions
Does Perfekt-Bau replace old Velux windows?
Yes, with Fakro replacement packages matched to Velux size codes, flashing included.
How much is shipping?
About 7.50 euros for parcels and 49.90 euros for a window by freight.
Can I pay on the invoice?
Yes. PayPal, card, financing, and prepayment are also offered.
Does it ship outside Germany?
Austria, yes. Elsewhere, ask.
Are the reviews good?
About 720 on Trusted Shops, mostly five stars, with praise for delivery and price.
Final Verdict
Perfekt-Bau is a proper merchant with a website, not a website pretending to be a merchant. For a roof window replacement or an attic insulation job, it's one of the better-priced options in Germany, and the replacement packages are a clever product. Find your window code, check the parts on arrival, and order well before the roofer's date.